Modern Sherlocks

There are a plethora of moving pieces involved in solving crime, and those behind the scene play a large part in the application of justice.

For National Forensic Science week, the Department of Public Safety Forensic Crime lab in Austin– which services all of Central Texas, including San Marcos, lifted the curtain to provide the public a peek into what it is that they do.

Each department has its own specialization and plays its own pivotal role, which in concert can uncover the who, what, where, when and how of a crime.

The tour began in the friction ridge lab, where Isabel Brownlow relayed the process behind uncovering latent fingerprints.

“On the palms of your hand, the fingertips [and] the soles of your feet there is skin that is different from the rest of your body,” Brownlow said. “It’s called friction ridge skin. It is corrugated and rough in appearance. There are raised portions called ridges [and] valleys that are called furrows, and along those raised portions … there are really small, minute sweat pores that exude sweat and also along those ridges collect sebaceous materials.”

Brownlow added that if a surface is touched, the materials along the ridges can be transferred onto it— leaving a fingerprint. If the material containing a fingerprint is not porous, they said the fingerprint will stay on top of the surface, whereas with a porous material, it will soak in–each requires a different form of processing. They said one of the processing techniques involve superglue fuming, in which the fumes adhere to the moisture left behind in the print–making the fingerprint visible and white.

Further along in the tour, Evan Flance talked about computer, mobile and vehicle forensics. Regardless of the device, Flance said a copy is created, which will be used for investigation purposes. They added that car stereo systems allow for a plethora of extracted data like phone data-even when the person has not given the device permission–and GPS data.

The other section of that lab is dedicated to forensic multimedia–audio and data forensics–and information was provided by Elinor Hehir on the functions of that department. There are various techniques to enhance video and audio, which they said can have beneficial impacts for extracting evidence. Hehir added that passwords can be bypassed by forensic software to allow for data extraction– even for deleted data.

“The bulk of our requests come from forensic video and audio clarification,” Hehir said. “Video is about 75% of what we get, but it’s clarifying subjects, objects, license plates, the scene, the make and model of the vehicle–pretty much anything in the video that they want to be seen better.”

Austin Ondijo was the initial presenter for the firearms department, particularly the firearms and toolmarks section.

Ondijo said primarily they are given bullets or casings and a firearm and tasked with concluding whether the bullet was fired from that gun. They have a water tank and a cotton box for test firing; the cotton box is packed tightly with cotton and used for higher velocity items.

“Water doesn’t compress and thus we’re able to slow down the bullet without it being fragmented,” Ondijo said. “And we recover it in a condition where … it’s pristine enough that we can compare it.”

Ondijo said that once compared, if sufficient agreement is found between the marks found on the known with the unknown bullet then a positive identification can be made.

Ryan Christopher showed the group how to restore a serial number from a firearm that someone has attempted to ablate using a magnetic process— which only works on steel– and a chemical process–a destructive and permanent process, which can be done on any metal. Christopher added that the firearms department also works with distance determination or discovering how far away a weapon was when it was fired.

“When it is fired, it’s not just the bullet that is leaving the muzzle,” Christopher said. “There’s also all sorts of residues such as gunpowder and lead and other things, and these residues are going to exit in a cone shaped pattern.” They added that known values are used to calculate the distance, and their findings are given in a range [e.g., one to two feet].

The Combined DNA Index System, more commonly referred to as CODIS, is a system, which Mario Mora said is used for comparing unknown DNA from a crime scene with known samples across three tiers: local casework labs, state DNA Index and the national DNA Index.

Shekinah Cooper said samples can be collected from all registered sex offenders, and as of September of this year, anyone who is charged with a felony.

Jessica Morey said the DNA section involves the extraction of DNA or partial- DNA profiles from crime scene items for comparison with known samples. They added that the first step is to screen the evidence for the presence of biological materials; there are several chemical tests that can be used to identify the presence of said materials.

Once identified, they take a small portion of the stain or a swab of it and put it into a tube with liquid, which is then processed robotically by utilizing extraction techniques–chemicals and heat are applied to break the cell open and release the DNA.

Capillary electrophoresis is used, which Morey said creates a graphical representation of our DNA profile– called an electropherogram.

“Once we have a DNA profile from our evidence … we’re going to look at how many peaks are in each of the locations,” Morey said. “Since you get some DNA from your mom and some from your dad, generally that most that someone is going to have at one location is two peaks or two different sequences of DNA … If we see more than two peaks at one location, we would say that there is more than one person contributing DNA to this profile.”

The seized drug section focuses on drug identification and quantity, which Tres Guerra said can be helpful in determining the penalty group it belongs to. One primary identification test is a color test, which they said involves adding a reagent to the unknown drug; it will turn different colors depending on the drug in the sample.

Guerra added that a more precise drug identification is a gas chromatography mass spectrometry–GCMS for short. They said you dissolve the drug sample in a liquid and pass it through a very long, thin tube called a glass capillary column, which is approximately the length of a football field.

“As those things enter this column, they’re going to go around and around,” Guerra said. “They’re going to be in a really hot oven that is going to heat up with time. So what happens is, some things are going to travel faster than others.” They added that a mass spectrometer at the end of the tube takes the molecule and breaks it into pieces–each molecule will break into the same pieces every time, which can be traced back to the original molecule.

For more information on the DPS Crime Laboratory go to dps.texas.gov/section/ crime-laboratory.