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00:06Early one morning, in a deserted area outside of Phoenix,
00:11a motorcyclist discovered the body of a young woman.
00:15She had been beaten, bound, strangled, and possibly raped.
00:21The surrounding plants would tell more about her killer
00:25than any other single piece of evidence.
00:39The End
01:02When investigators from the sheriff's department arrived at the crime scene,
01:06they gathered every possible piece of evidence.
01:10The victim was nude, except for a pulled-up tank top
01:13and a t-shirt wrapped around her neck,
01:16which was probably used to strangle her.
01:19Her wrists and ankles were loosely bound with shoelaces
01:23and what looked like picture-hanging wire.
01:28Nearby, investigators found a syringe, some articles of clothing.
01:33Then they heard some evidence.
01:46It was a pager found deep in the grass a few feet from the body.
01:52The discovery of the pager triggered a larger search
01:56and the photographer took some aerial photographs.
01:59There appeared to be a circular area of matted grass
02:03where an altercation possibly took place.
02:14Police took the victim's remains to the medical examiner
02:17for identification and autopsy.
02:20A fingerprint search identified the victim as 30-year-old Denise Johnson,
02:26a single mother of two young children.
02:29She was born and raised in an area of Phoenix known as the Projects.
02:33She wasn't a bad girl.
02:36She, some of her friends, I think she got with the wrong friends.
02:41I ain't gonna say they made her do these things, no.
02:45She hung around with people that liked to party, drink,
02:49and I don't really know what they were doing,
02:52but she, you know, she was out there in the world
02:54with people that did drugs, I'm sure,
02:58and sometimes I think she trusted too much.
03:01Denise made her living on the streets of Phoenix.
03:04She had a history of short-changing truck drivers
03:07and various drug deals at local truck stops,
03:09which earned her the nickname Twist Mama.
03:13Her friends cautioned her that her lifestyle
03:16was probably gonna find her in a lot of trouble someday,
03:20and eventually it did.
03:22But who ended Denise Johnson's life?
03:25The investigation began with the pager
03:28found lying near the body.
03:30It belonged to this man,
03:32a local trucker named Mark Bogan.
03:37He said that on his way home from work the night before,
03:40he stopped to make a phone call.
03:42That's when he met Denise Johnson for the first time.
03:45Hi, how you doing?
03:46Hello there.
03:47Bogan said she asked for a ride to the interstate.
03:50Why not?
03:51Thanks.
03:54Once inside the truck, she made some sexual advances.
03:58They pulled off the road and had consensual sex
04:01in the cab of his truck.
04:11Afterwards, as he was dropping her off,
04:13he said she attempted to steal some of his things
04:16off the dashboard.
04:17Oh, I had a really good time.
04:19Oh, so did I, baby.
04:20Did you?
04:21Oh, always when I'm in the company of a lovely lady.
04:25I would really love to have my wallet back.
04:28After a brief scuffle, he retrieved his wallet.
04:31She got out and left on foot.
04:34Bogan said that was the last he saw of her.
04:38The next morning, he noticed his pager was missing,
04:41assumed he had lost it,
04:43and called the pager company to report it missing.
04:47During the interrogation of Mark Bogan,
04:49investigators noticed scratch marks on the side of his face.
04:53If there were scratches on the suspect's face,
04:55then you would expect that if those were, in fact,
04:58inflicted by fingers or fingernails of the victim,
05:02there should be some residue of either the skin cells
05:05and or maybe even blood under the fingernails.
05:07The autopsy of Denise Johnson revealed no skin or blood
05:10under any of her fingernails.
05:13The medical examiner found that Denise Johnson's death
05:16was caused by asphyxiation due to strangulation.
05:20Blood tests showed cocaine in her system.
05:24However, there were no signs of any type of sexual activity.
05:28There was no semen found, no foreign hair,
05:31clothing fibers, or saliva found anywhere on her body.
05:35The autopsy told investigators how Denise Johnson died,
05:40but provided no clues about her killer.
05:43Their one suspect, Mark Bogan, was apparently a dead end.
05:49The sheriff's office had not only a murder, but a mystery.
05:58On the day after police discovered Denise Johnson's body,
06:02homicide detective Charlie Norton was assigned to the case.
06:05I decided that it would help me as the investigator
06:09to go out and familiarize myself
06:11with the scene where the body was found.
06:14Denise Johnson's body was discovered
06:16in a remote part of Maricopa County,
06:19about a half an hour away from downtown Phoenix.
06:22Charlie Norton was looking for anything out of place or unusual,
06:27anything that might have been overlooked the day before.
06:31Then he saw it, something peculiar, on a Palo Verde tree,
06:36just a few feet from where the body was found.
06:39I had parked my car on the pavement.
06:41I noticed that there was a branch that was hanging over.
06:47And when I looked at that branch,
06:49I noticed that there was a fresh abrasion.
06:52And I had no idea what it might mean.
06:56But I took a picture of it.
06:58Then I took some beans off of that particular tree.
07:02Meanwhile, investigators confiscated Mark Bogan's truck
07:05to look for possible evidence linking him or his truck
07:08to the crime scene.
07:10It was completely clean.
07:12No fingerprints, semen, blood, saliva, hair, or clothing fibers.
07:17No evidence at all that Denise Johnson was even in the truck.
07:22But when investigators and police photographers
07:25looked in the back of the truck,
07:26they made an interesting discovery.
07:29They found two bean pods from a Palo Verde tree.
07:35Was it possible that Bogan's truck
07:38brushed against the Palo Verde tree at the crime scene,
07:42causing two bean pods to drop into the back of the truck?
07:46The problem was, Palo Verde trees are very common in Arizona.
07:50There are tens of thousands of them in the Phoenix area alone.
07:54But Charlie Norton's boss had an idea
07:57to see if DNA testing could match the bean pods
08:02from Bogan's truck to the tree
08:04with the abrasion at the crime scene.
08:06I suggested to Charlie at the time, I said,
08:09you know, I said it would be a real good idea
08:11if we could find someone,
08:14somewhere in the United States
08:15that is involved in DNA testing the plant life.
08:19And I said, what the hell have we got to lose?
08:21You know, where are we going to go from here?
08:23What's the number for ID?
08:24Norton started working the phones,
08:26calling scientists all over the United States.
08:29I've got answers like it couldn't be done
08:32to maybe it could be done,
08:35and that if it could be done,
08:37that the cost would be prohibitive.
08:38Fifteen telephone calls later,
08:40he found someone who offered some hope,
08:43ironically, just 100 miles away,
08:45at the University of Arizona in Tucson.
08:48I saw that as sort of a public service thing
08:50that we could do,
08:51that we'd show some of this science
08:53is relevant to people
08:54in maybe a way that's not quite as obvious
08:56sometimes through agriculture.
08:58Could DNA really show
09:00that one plant or tree
09:01was different from another,
09:03even though they were the same species?
09:06DNA is present in all cells of all living things.
09:09It's a little like a computer program
09:12containing all of the information necessary
09:14to create a living thing.
09:17All humans have different DNA profiles
09:19except for identical twins.
09:22In the early 1980s,
09:24Dr. Alec Jeffries, a British scientist,
09:27discovered a test
09:28that made it possible
09:29to identify an individual's DNA profile.
09:33Jeffries' breakthrough technique
09:35was first used in a criminal case in 1986.
09:39But plant DNA
09:41had never been used in a criminal case,
09:44and scientists weren't even sure
09:46they could figure out a way
09:48to extract DNA
09:49from the Palo Verde seed pods.
09:51Well, we certainly use fingerprinting
09:53a lot in agriculture,
09:54but we've never looked
09:56at this particular species,
09:57this tree.
09:58Nobody has probably ever done
09:59much biology on it at all.
10:01Prosecutors had circumstantial evidence
10:04linking Mark Bogan
10:05to Denise Johnson's murder,
10:07but they needed something more definitive.
10:10They knew they would have to prove
10:12that Bogan was at the crime scene,
10:15and the Palo Verde pods
10:17were their best chance.
10:19The scientists had no idea
10:21that their research would be
10:23the cornerstone of a murder case.
10:28The Arizona Sheriff's Department
10:30wanted to know
10:31if there was any way
10:32scientists could match
10:33the two seed pods
10:34found in the back
10:35of Mark Bogan's truck
10:37to the Palo Verde tree
10:38next to where they discovered
10:40Denise Johnson's body.
10:43But there were thousands
10:44of Palo Verde trees
10:46in the Phoenix area alone,
10:48and there had never been
10:49a DNA test
10:50on this type of tree.
10:52We had to learn
10:52how to do the analysis
10:54so that we could say,
10:55do trees look different
10:56from each other
10:57in this species?
10:58Because what we wanted to know
10:59was not was this
11:00a Palo Verde tree,
11:01but could I match it
11:02to that specific tree?
11:04Dr. Helen Jarrus
11:05used what is known
11:06as a randomly amplified
11:08polymorphic DNA technique,
11:10or RAPID.
11:11This is a less common test
11:13than RFLP,
11:15the one used in searches
11:16for human DNA.
11:18One of the great things
11:19about RAPIDS is
11:20is that you're able
11:21to know nothing
11:22about an individual species
11:24or type of organism.
11:25You don't have to have
11:26any prior knowledge about it.
11:28All you have to do
11:28is get DNA,
11:29and the method works.
11:31The test begins
11:32by removing the beans
11:33from their hard outer shell
11:35or pod.
11:36Seeds have DNA
11:37both from the mother tree
11:39and other trees
11:40that would have pollinated it,
11:41so we need to get rid
11:42of those and just use
11:42the pot material,
11:43which will only have DNA
11:44from the mother tree.
11:46The shells are put
11:47into liquid nitrogen,
11:49making them brittle
11:50and easier to grind
11:51into a fine powder.
11:58A chemical solution is added
12:00and the DNA floats free,
12:03a sticky bundle
12:04of complex molecules.
12:07The sample amount of DNA
12:09from a seed pod
12:10is too small for analysis,
12:12so scientists increase
12:13the sample size
12:14by copying the DNA strand.
12:17They use a technique
12:18called polymerase chain reaction,
12:21or PCR.
12:23The copying process
12:24takes place
12:25in a DNA thermal cycler.
12:28Within a few hours,
12:29this technique
12:30multiplies the DNA
12:31millions of times.
12:33The DNA is then placed
12:35into various lanes
12:36of a gel
12:37with a dye added
12:38and then subjected
12:40to an electrical field.
12:42Under ultraviolet light,
12:44it's possible to see
12:46how the electrical current
12:48draws the negatively
12:49charged fragments
12:50through the gel
12:51to the positive end
12:52at the top.
12:55The results resemble
12:57a barcode,
12:59the genetic fingerprint
13:00of a Palo Verde tree.
13:03These fingerprints
13:05enabled Helen Jarris
13:06to make an important discovery.
13:09The two pods
13:10found in Mark Bogan's truck
13:12matched each other.
13:14And they also matched
13:16the pods taken
13:17from the tree
13:17at the crime scene,
13:18the tree next to where
13:20Denise Johnson's body
13:22was discovered.
13:23Every other Palo Verde tree
13:25tested had a completely
13:27different DNA profile.
13:28It was the result
13:30that investigators
13:31and the district attorney
13:33had hoped for.
13:34It wasn't the criminal itself,
13:35but it was a particular tree
13:36that we had to identify,
13:37and in fact,
13:39we had matched that up.
13:40He was able to
13:43take the original samples,
13:45take a part of the samples
13:48from the pickup truck,
13:50determine that those two pods
13:52came from the very same tree.
13:54Then he compared those
13:56with samples from all 12 trees
13:58and matched it
14:00to a tree
14:02there at the crime scene,
14:04not knowing that the tree
14:05had the scrape on it
14:06to which he matched it.
14:07But there were only 12 trees
14:10in the initial test,
14:11and the prosecution felt
14:13that wasn't a large enough sample.
14:15They needed to show
14:16a potential judge and jury
14:18that all of the Palo Verde trees
14:20in Arizona
14:21had a different DNA profile.
14:24So the district attorney
14:26sent Helen Jarris pods
14:27from 100 different trees,
14:30asking him to prove
14:31that each had a separate
14:33and distinct DNA profile.
14:36and he tried
14:37to trick Helen Jarris.
14:39I did not tell
14:40Dr. Helen Jarris
14:41that I had gone back
14:42out to the scene,
14:43had a deputy take
14:43a sample from the same tree
14:47which had the scrape on it.
14:48Dr. Helen Jarris proved
14:50that each of the pods
14:51had a different DNA profile,
14:54and he also discovered
14:55the prosecution's trick.
14:57I called him
14:58and I was a little concerned
14:59because, you know,
15:00well, we could tell
15:01all these trees apart
15:02and so forth,
15:03but we put the sample back in
15:05and it looked like
15:06it matched one of these
15:07supposedly random trees
15:08that they'd gone out and done.
15:09It's almost like
15:10a touchdown in the end zone.
15:12I knew it.
15:13I knew he had hit on it.
15:14Out of 20 other samples
15:15that he had tested
15:16on one gel,
15:17he hit and matched perfectly.
15:20Police arrested Mark Bogan
15:21and charged him
15:23for the murder
15:23of Denise Johnson.
15:25He entered a plea
15:26of not guilty.
15:28But the question remained,
15:30would this new DNA evidence
15:33be admissible in court?
15:35No one had ever introduced
15:37plant DNA as evidence
15:39in a criminal trial anywhere.
15:41We held a preliminary hearing
15:43before the judge only
15:44to review the scientific evidence
15:47to see whether or not
15:48it was evidence
15:49that was generally accepted
15:51in the scientific community
15:52as both valid and reliable.
15:54For three days,
15:55without a jury on hand,
15:57lawyers and scientists
15:58argued whether plant DNA
16:00should be admitted
16:01into a criminal trial
16:03for the first time ever.
16:05What all of the scientists
16:06agreed about
16:07was that plant DNA,
16:10like human DNA,
16:11was unique to each plant
16:14and if properly tested,
16:18could distinguish
16:20one Palo Verde tree
16:22from another Palo Verde tree.
16:23and there seemed
16:24to be no dispute about that.
16:26Judge Bolton denied
16:28the defense motion
16:29to prohibit
16:29Dr. Helen Jarris' testimony,
16:32thereby allowing the DNA evidence
16:34to be admitted at the trial.
16:36In setting a precedent,
16:38Judge Bolton
16:39had made DNA history.
16:42We were the first criminal case
16:44in the country
16:45that used a DNA comparison
16:47of plant material
16:49to, uh,
16:51as a piece of evidence.
16:52Now, armed with the potent weapon
16:55of a DNA fingerprint,
16:57the prosecution went to trial,
16:59attempting to prove to a jury
17:01that Mark Bogan
17:03murdered Denise Johnson.
17:07What happened to Denise Johnson
17:09on the night of May 2nd, 1992?
17:13The prosecution believed
17:15that Mark Bogan
17:16met Denise Johnson
17:17at a phone booth.
17:19Hi, how you doing?
17:21They spoke briefly
17:22and Denise asked for a ride.
17:24Sure, why not?
17:25Thanks.
17:35They drove to a deserted location
17:37for what was going to be
17:39a consensual sexual encounter.
17:50How would you like
17:51to have some real fun?
17:52Bogan asked Denise
17:54if she would agree
17:55to some light bondage
17:57and tied her wrists
17:58and ankles
17:59with some picture frame wire
18:01and shoelaces.
18:03Some of Bogan's ex-girlfriends
18:05would testify
18:05that he enjoyed bondage.
18:08And another witness
18:09told investigators
18:10that she saw
18:12the same type of wire
18:13in the cab of his truck
18:14just a few days earlier.
18:17No.
18:18No, stop it.
18:19At some point,
18:20Denise Johnson objected
18:22to what was happening
18:23and asked Bogan to stop.
18:25Johnson got out of the truck
18:27and tried to run
18:28with Bogan fast behind.
18:31Quickly,
18:32the situation turned violent.
18:34The two struggled
18:35in the open field.
18:36Bogan lost the pager
18:38he carried on his waist,
18:39which fell into the high grass.
18:42Bogan strangled Johnson
18:44with her own T-shirt.
18:46Then he dragged her body
18:48under some nearby bushes
18:49and left.
18:51As Bogan drove away,
18:53his truck brushed
18:54against the Palo Verde tree,
18:56leaving the abrasion.
18:58Two seed pods
18:59dropped into the back
19:01of his truck.
19:04An eyewitness
19:05saw a white truck
19:06similar to the one
19:07Bogan owned
19:08coming out of the road,
19:10leading from the crime scene,
19:11going through a stop sign
19:13and speeding off
19:14in the direction of Phoenix.
19:16The witness said
19:17it was about 1.30 in the morning.
19:20Bogan lived 18 minutes
19:21from the area,
19:22and his wife told police
19:24she awoke
19:24as Mark returned home
19:26just after 2 in the morning.
19:29Most of the evidence
19:30against Mark Bogan
19:31was circumstantial.
19:33The lost beeper,
19:34the picture frame wire,
19:36his interest in bondage,
19:38and the witness
19:39who saw a white truck
19:40in the vicinity
19:41of the crime scene
19:42the night of the murder.
19:44But the most critical evidence
19:47in the case
19:48was the plant DNA.
19:50There wasn't a fingerprint,
19:52there wasn't a drop of blood,
19:53there wasn't a hair.
19:55There were none
19:55of those things
19:56that anybody could say
19:58were part of the victim's body
20:00found,
20:01must have been left
20:03by the victim
20:03on the defendant
20:05or on the defendant's property
20:07or vice versa.
20:08He had admitted
20:09to the detectives
20:10that he'd washed his truck
20:11the next morning.
20:12He got rid of all
20:13of the evidence
20:13in the truck
20:14except for 2 Palo Verde pods.
20:17They needed evidence
20:18that placed Mark
20:19at the scene
20:20because he did have
20:21a credible story.
20:22As a prosecutor,
20:23I had a mantle of evidence
20:25that I wanted to place
20:26upon the shoulders
20:26of the defendant.
20:28The Palo Verde pods
20:31took the mantle
20:32by the drawstring
20:34and wrapped it
20:35around his neck.
20:37Unable to challenge
20:38Dr. Helen Jarras' findings
20:40themselves,
20:41the defense challenged
20:42the evidence,
20:43implying the pods
20:44were planted
20:45in the back
20:46of Mark's truck.
20:47But investigators said
20:49the seed pods
20:50were found
20:50in Bogan's truck
20:51before samples
20:52were taken
20:53from the crime scene.
20:54If I was going to plant
20:56evidence,
20:56I would plant something
20:57that I know
20:59that I could match
21:02later on
21:03and probably be
21:04a little bit more
21:08assured of a conviction.
21:10The jury found
21:11Mark Bogan
21:12guilty of murder
21:13in the first degree.
21:15He was sentenced
21:16to life in prison
21:17without parole
21:18for at least 25 years.
21:21The appellate court
21:22upheld the verdict.
21:24Mark Bogan
21:25continues to maintain
21:26his innocence
21:27and the appeal process
21:29is continuing.
21:30I'm trying to forget
21:31this case
21:32because I'm the only person
21:33on the planet
21:33that lost to a plant.
21:35It was something
21:37that hadn't been done before,
21:39something that
21:40was certainly
21:43very different
21:44from the routine things
21:46that we do every day
21:47as judges.
21:48But I love my daughter
21:49very much.
21:50I love all my children.
21:53But it's something
21:54we just have to
21:56go through.
21:57It's done.
21:58I don't know
21:59what in the world
22:00that could have
22:01tripped him off
22:02to hurt her like that.
22:04I don't know.
22:06But I hope
22:07one day we'll find out.
22:10God bless you.
22:12God bless you.
22:20God bless you.
22:39Transcription by CastingWords
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