Tip:
Highlight text to annotate it
X
>> Glennn: I get to introduce you Marianne so give me a second.
Our next speaker is Marianne Stam.
She's currently the acting supervisor
for the Trace Evidence Firearms and Crime Scene Unit
at the California Department
of Justice Criminalistics Laboratory in Riverside.
She's worked for that agency for 23 years and has worked
in the trace evidence section for 21 of those years.
She's a member of the SWGMAT Committee since 1996.
I beat you by two years on that.
And she serves on the paint subgroup committee.
And, one thing you probably don't know
about Marianne is she raises chickens.
[ Laughter ]
Marianne's going to be speaking on the value of diatoms
and botanical evidence in a police brutality case
and a technique for the collection
and examination of diatom evidence.
>> Marianne: Thank you Glennn.
I just wanted to say that the chickens are pets not lunch,
okay.
Today I'm going to speak to you about a case in which I had
to know something about the case in order to be able
to corroborate this person's story.
And so, just going back to what Tom was saying.
You can't operate in a vacuum.
This case involved a man who was walking home
in the early morning hours of July 5th 1997.
He was walking through downtown Riverside, when he was stopped
by three Riverside Police Department officers
for allegedly being intoxicated.
The officers, according to the man's story,
instead of taking him to the jail, they drove him
about a mile in the opposite direction
to a park area called Fairmont Park
that happened to have a lake in it.
And the lake is called Lake Evans and it's in Riverside.
The man claimed that they dragged him out of their unit,
they dragged him through some sandy,
short sandy area along the beach, the edge of the lake,
and they threw him in the lake.
Now, this is Lake Evans.
It's all, it's a manmade lake
that was basically made in the early 1900s.
And that's where all of the plants were brought in
and planted around the lake to make the park.
And the lake along this edge right here, there's a road
that actually goes around the lake.
And, back in that area is where the man claimed
that the officers drove him, dragged him out of the vehicle,
beat him up, and threw him in the lake.
So, this is the picture of the area.
And the road is right here.
This is the shoreline area and the lake's over here.
And this is an area over here also.
I just, I'm showing this because I also, I collected samples
and I collected samples from across the street as well.
Now, this shows, kind of,
just nice pictures showing the different varieties of plants,
how pretty it can be and that it's basically all brought
in plant material or trees.
I was asked to, called up by the Riverside Police Department a
few days after this happened.
And, they had gone to the Lawrence Berkley Laboratory
and inquired about having an analysis done.
But, due to the cost of having the analysis done,
which would have been water chemistry, they decided
to call the lab and see if they could get something done
for cheap which is basically free.
So, they asked me was there anything that, you know,
we can do to show that this man may actually be telling
the truth.
So, they wanted me to look for something that showed
that he had been in or around the park and the lake.
So, my first thought to the officers was well,
I'll look for diatoms and I'll look for plant material.
So, and they happened to have the clothing of the victim,
but unfortunately they did not have the clothing
from the police officers because they didn't actually start
questioning the police officers for a couple
of weeks after this incident.
The man did go to the police fairly quickly.
He went, I believe, like the next day,
several hours after the incident.
So, the officers, in the two-week period,
had basically cleaned all
of their uniforms, had them dry-cleaned.
And so, I didn't, you know, get their clothing to work with.
But anyway, before I get into my analysis I just wanted
to divert a little bit into diatoms and what they are.
They're basically a single-celled algae
that have silicified cell walls.
And, many of the fossil type diatoms that we find
and the parts that are left behind from diatoms
that die are basically these silica-based cell walls.
There are, as of the latest information,
close to 100,000 species.
And the interesting thing is, some live as floaters also known
as pelagic in open water and others,
the water sediment interface
where they are ground dwellers or benthic.
These are some pictures of diatoms
that I got off the internet.
And, if you notice some are more round and some are elongated.
And, according to a diatom expert that I spoke to,
the shape can be an indicator of whether you're dealing
with a pelagic species
or a water sediment interface species.
And, by the way, I got back from China about three weeks ago.
And we went to a national park,
and there were actually living diatom algae that I got to see
which I probably would not have ever recognized except there was
a professor along who knew about diatoms.
So, it was kind of neat to see that.
But, anyway, back to the examples
of the diatoms as evidence.
They have been encountered for years in drowning cases
where pathologists look for them in the lungs of victims.
I've encountered them and they've also been encountered
for years forensically as fillers in matches and paint.
They are in soils where you have moisture.
And, they also have been used by environmental forensic work
as indicators of the environment
of water rich environments and environmental conditions
and changes in environmental conditions.
They've also been used as safe insulations.
My case approach was I got the clothing in from the victim
and I examined the clothing for the evidence indicating
A: that the clothing had been wet, because then that would be,
you know, one of the indicators that he may be telling the truth
that he was in the water at least.
And then, I looked for plant material and then the diatoms
because diatoms will be indicators
of a water rich environment often standing bodies of water.
So, anyway, so this is basically,
what I've already said that the investigator submitted
the clothing.
They wanted to corroborate the victim's story
and that the officers' clothing were not submitted
because of the duration of time between the incident
and the questioning of the officers.
So, evidence collected in the laboratory,
I collected the plant material.
I collected loose debris from the bags
that the clothing came in.
And, from the victim's clothing, my first act
for collecting trace was to use tape lifts.
The tape I used is a frosted form of Scotch Tape.
We use that because it isn't as tacky and sticky
as say fingerprint tape or clear tape.
And so, it's easier to get trace evidence off of it.
So, that's what we use that.
After I took the tape lifts, I did debris collection
by scraping and shaking the clothing.
And then, I also did cuttings of the stained areas
and of clean controlled areas from the victim's clothing.
I also went to Lake Evans with a botanist and the investigators
and I collected the following samples.
I collected lake water that was close to the shore near the site
of the incident, lake water from the middle of the lake,
sand samples from the shoreline near the site
and sand samples west and across the street from the site.
And, I also collected botanical exemplars with, of course,
the aid of the botanist.
The evidence analysis; my first thing was,
I examined the evidence that I had collected using visual
and stereo microscopy, polarizing light microscopy.
And then, the botanical evidence that was collected off
of the victim's clothes, I submitted to the botanist
and he was the one that analyzed the botanical evidence.
Well, I was trying to figure
out how would I find diatoms on clothing?
And so, I first tried looking at the scraped shaken debris
from the victim's clothes for the diatoms by mounting portions
on the debris that I had sieved in ultra purified water
and examining them under polarizing light microscopy.
I also looked at blanks of the ultra purified water to ensure
that I wasn't contaminating my sample before I even used
the water.
And, I found no diatoms in it,
nothing in fact that I could see.
And this, I tried this analysis for about two
to three days just looking through this stuff.
And, I didn't find anything that I could really see that looked
like what I, you know, had seen diatoms to look,
what diatoms looked like.
So then, I thought well, I'll take the tape lifts.
But, how am I going to look at them.
How am I even going to find the diatoms
on the tape lifts to examine?
So, I decided to try something.
So, I took the tape lifts, I cut them into smaller pieces,
and I took the taped ends, I rolled them
over the very end pieces, stuck those down so
that the sticky side was up on the slide, and then I mounted,
I put ultra purified water on a small portion of the tape,
just to see if it would work, on one of these lifts.
And, I put a cover slip on top.
And, I looked at it under PLM.
And within five minutes, I started finding diatoms.
So, at least, what this did was it allowed me
to visualize the diatoms.
And that was really, I was really glad that that worked.
And basically, I was interested in finding the presence
of diatoms to show that the victim was in
or near a standing body of water.
I, as I said, I went to a botanist,
gave him the botanical evidence, the University
of California Riverside Botanical Gardens Herbarium.
He was actually the curator of that herbarium and gardens.
And then, I contacted a diatom expert at the California Academy
of Sciences in San Francisco and sent him the diatoms
and the information to see what he could come up with.
And, of course, I also look at the exemplars
that I had collected from around the lake of the diatoms.
And, my findings, well there were diffused brown stains
on the victim's boots and jeans indicating
that they had been wet.
There were several diatoms on the tape lifts
of the victim's clothing that, to me, were similar
in appearance to the diatoms observed in the lake water
and in the sand samples surrounding the lake.
And then, that was confirmed by the diatomist.
And then, the botanist found leaves and cone scales
on the victim's clothing that were
from a Mexican Bald Cypress tree.
Well, Mexican Bald Cypress trees, as I found out were sort
of the national tree of Mexico.
And, as it turns out, these trees were imported
into Riverside in the early 1900s specifically
to be planted around Lake Evans.
The botanist knew of only one other of these types
of trees in all of Riverside.
And, that happened to be
at the Botanical Gardens about ten miles away.
So, finding these cone scales and plant material
from the Mexican Bald Cypress was the most significant piece
of evidence in this case.
That, combined with the diatoms from the clothing,
which there's a picture here of one.
Unfortunately, it's not a very good picture
because it was taken under a Polaroid before we had
digital cameras.
And I probably should have taken 35 millimeter.
I apologize for that.
And then, here's a diatom from the lake
that was identified by the diatomist.
And so, my conclusions are that the diatoms and botanical evidence
and the presence of the diffused stain showed that his,
the victim's clothing had been wet, provided strong evidence
that the victim had been in Lake Evans or its immediate vicinity
when you combine all the evidence together.
The method that I used worked as a search method.
I'm sure other people have probably used similar methods.
But it actually, with the tape lift idea,
it helps to preserve positional information
if that ever becomes important in an investigation.
In this case, it wasn't, but I figured
in other cases you might, you know, be able to use that.
My mounting method; just a real simple diagram,
I have the slide here.
Here's my piece of tape.
I took the ends and rolled them under so
that the sticky ends were stuck to the slide.
I put the here say, one of the areas I'm looking
at on the tape lift, I just put a little bit
of the ultra pure water on and put a cover slip on,
put it under the PLM and examined it
and found the diatoms.
The consequences, all three police officers were fired
and all plead guilty to assault charges.
And, I'd like to thank the UC Riverside Herbarium Curator Andy
Sanders and the diatom expert from the California Academy
of Sciences Pat Kociolek.
And, I also want to point out how important it really was
to keep contacts with academic communities
because I've used Andy in a number of cases.
And I haven't had the pleasure to use Pat
in another diatom case yet.
And, that's it.
[ Applause ]
>> Glenn: Does anybody have questions for Marianne.
>> Nice job.
>> Marianne: Oh thank you.
>> Glenn: I think she does have an announcement to make
or something else to say.
>> Marianne: Oh I do.
Some of you may have seen the announcement
for the International Soil Forensics Conference
that will be next year in Long Beach California
in early November 2010.
I'd like to encourage all of you to contact me
if you want information regarding that meeting.
It is affiliated with the International joint meeting
of the Soil Science Society of America,
I believe it's called the American Agronomical Society
and the Crop Science Society of America.
It is its own separate part of that conference and it's kind
of like a mini conference in the larger conference.
So, if anybody's interested just let me know.
It's on soil forensics and it is an international meeting.
>> Glenn: Guy do you have a question?
>> Guy: Guy [inaudible] from the Michigan State Police.
Just out of curiosity, the conclusion in your report,
had you not had the botanical evidence,
what type of statement would you have said
about that evidence without that?
>> Marianne: Well, I would've probably left it more
up to the diatom expert to write a report
and send it to the investigators.
I probably would've said I found diatoms and the fact
that there were diffuse wet stains on the clothing.
And, I probably, most likely, would've looked more
and sent more botanical evidence over to an expert
in water botanical plants because there was a lot more
of that kind of plant material as well.
So, I would've backed off some although I would've probably
stated that the diatoms indicate he was in or close to a moist,
you know, standing body of water or a moist environment, so.
>> Doreen: Hi, I'm Doreen Hudson
from the Los Angeles Police Department.
And I might have missed this, but I'm not really clear
on how placing this victim at the location
of the lake was incriminating to the officers.
Was there something contextual in their version of events
that proved them to be untruthful?
I missed a little link there.
>> Marianne: Yes, the police officers made statements
that they had not been around the lake.
They said that they stopped the individual but let him go.
And that was about a mile away from where the lake was.
In addition the investigators were questioning this guy
because they didn't know if he,
the Internal Affairs Investigators, they didn't know
if he was actually intoxicated or not.
And so, they wanted some independent evidence
to corroborate a story as well because they didn't know whether
to trust his story or not, so.