Houston Criminal Defense Lawyers



More HPD Crime Lab Problems; This Time it’s the Crime Scene Unit


police-850054_1920Yes, I said HPD Crime Lab rather than Houston Forensic Science Center. Despite the fancy new name and claimed independence, it’s the same old game. This time the Lab commissioned an audit of its crime scene unit related to officer-involved shootings. The purpose of the audit was to address complaints by the District Attorney’s Office and HPD’s own homicide division. The audit focused solely on the crime scene unit and their performance during the investigation of officer-involved shootings. And the results reveal anything but independence.

Hat tip to the Houston Chronicle for revealing this audit and reporting on its findings.

Set aside for a minute the technical problems with the crime scene unit, the audit highlights a continued lack of autonomy expected of an independent and forensic agency. This “independent” crime scene unit is comprised of 26 employees: a civilian director, a civilian administrative employee, four civilian investigators, and 20 HPD officers and sergeants. 77% of their staff are commissioned officers from the Houston Police Department – the very entity it largely investigates and is supposed to remain independent of. The crime scene investigators even wear HPD uniforms or insignia as they collect evidence and process scenes. They are in fact HPD officers and employees who are subject to transfer out of the crime scene unit and back into the regular ranks. That’s not an independent agency.

Additionally, the crime scene unit personnel are directed largely by the homicide detectives on the scene as well as the officer involved in the shooting. The audit noted that the decision to stop evidence collection was made to appease the homicide detective who determined he “had enough” evidence and an iron clad case. The involved officer, the shooter and apparent target of the independent investigation, is present telling his colleagues “what happened,” it is difficult for crime scene investigators to look past those words and search for additional, or dare I say contradictory, evidence.

On a side note, this is the same bias faced by prosecutors and their investigators – they too are on scene and inside the scene listening to the officer describe what happened. They too will have difficulty looking past those words. Outside of the walk through and witnessing the charting of the officer’s weapon, they sit back and wait on reports from the crime scene unit, homicide, and internal affairs. They conduct no other independent investigation. Instead, they serve as only a somewhat independent review.

Having been on many of these scenes, both as a representative of the District Attorney’s Office and as an involved officer’s legal counsel, the “walk through” by the officer always leads the evidence collection. Sure the scene is secured prior to the walk through and some evidence may already be marked, but everyone is looking for the officer’s rendition to know where else to look and what might be there. To be fair, where a foot chase proceeds a shooting, the scene can be rather large and spread out, necessitating some direction by the officer involved. But for independence, his involvement and direction in the scene must be minimal. Investigators must be free to disregard his words and explanation as they search independently for evidence.

Back to those technical problems: the internal audit found that crime scene unit technicians lack basic forensic skills and training. That’s kind of a big problem given their role in evidence collection. They are not trained specifically in bloodstain patterns and trajectory analysis. This could mean they miss the significance of bloodstains found on the scene. They may guess at or misread an angle of fire as a bullet traveled from the officer’s gun through an object or into a person. They overly rely on two-dimensional photographs to document facts rather than notes, data, and measurements. In fact, they rarely use the sophisticated FARO Focus 3d X330 laser scanners available to capture millions of measurements within the scene and provide a three-dimensional view.

This is not to say that skills and training cannot be improved; it’s simply to point out that they must be strengthened. There is no need for their training to come at the Houston Police Academy. They need not work alongside and with “colleagues” who share the same experiences, badge, and paycheck. Much like the Harris County Institute of Forensic Sciences hires its own employees, the Lab’s crime scene investigators should not be linked to or tied to the Houston Police Department – at least not if they want to claim independence.


view and download the audit report: Findings of CSU Audit


DNA Errors: Big Deal or Not?


Have you seen the news? The FBI has announced errors in its database which is used across the nation and in Texas. In two prior blog posts (on separate sites), I addressed this issue.
August 7, Just How Accurate is DNA?, HCCLA.org (with memo downloads)
September 18, FBI DNA Calculation Errors, HCCLAtv.com

Today, Fox 26 News visited with me to get a perspective on just how big this problem is.
As I told Andrea Watkins, Fox26 News, the problem will be large simply because each case will have to be identified and then reviewed to see what impact the DNA results may have had on a particular plea-bargain or jury verdict. Ultimately, this will amount to thousands of cases locally as the errors have existed and been perpetuated since 1999.

The problem is that errors in the statistical database could have caused an inflated reliance on a match. For example, instead of the probability of a particular DNA sample matching a suspect or defendant being 1 in 1 billion, it could be that it is only a 1 in 100 chance of belonging to the same person. This certainly changes the landscape and statistical chance of the DNA being left by the same person.

This problem is compounded in “mixture” cases. A mixture case is where two or more persons have contributed to the sample. We often see swabs collected from crime scenes where the analysis reveals the DNA of two individual people. The statistical errors, once corrected, can cause a scientific result which once included a suspect to now exclude that same person because of the lack of strength in the probability of the result matching. (I hope that makes sense. Essentially, science sets limits. If the probability falls below the lower limit, it is no longer considered a scientific match; so if the recalculation falls below, it is no longer considered reliable.)

Of course correcting each DNA statistical calculation will not ultimately help every defendant or suspect. But i will change the scientific reliability in some cases; therefore, each case will have to be analyzed to see whether or not it is affected.

This is a huge undertaking. It will take time. And, it will certainly add to the backlog in crime labs and the overall turn-around on testing old as well as new evidence.

In any event, I’m staying on top of this and will continue to report what I can.




John Denholm had a recent Felony DWI-3rd where the blood analysis was conducted by the Harris County Institute of Forensic Sciences (IFS). The IFS says they are impartial and are only on the “side of science.” In this case, they were.

Here, the accused had exercised his constitutional rights not to cooperate with law enforcement and provide evidence against himself. He would not participate in any Standardized Field Sobriety Test, refused to answer any questions, and refused to voluntarily submit a specimen of his breath or blood. The arresting officer obtained a search warrant and blood was drawn approximately two hours after the stop. When tested, it was reported out as a blood alcohol concentration (BAC) of 0.083 ± 0.007 g/100 mL. In other words, the blood alcohol concentration fell within the range of 0.09 to 0.0796. Clearly, retrograde extrapolation would be an issue in the case.

Photo of the evidence from HCIFS

Photo of the evidence from HCIFS

Doing his due diligence before trial, John scheduled a meeting with the analyst, Josie Hollowell. When he arrived at the IFS, he was greeted not only by Hollowell, but by both the Technical Reviewer, Patricia Small and the Expert Reviewer, Dr. Jeff Walterscheid. During the meeting, the discussion included the blood being first reported out at 0.098. Per the IFS protocol, a 2nd analysis was required to confirm the 1st. However, the 2nd  analysis reported out at 0.083, which necessitated yet a 3rd analysis of the same sample. This time the blood reported out at 0.086.

IFS protocol dictated only the lowest result is sent to the State. The blood was reported out at 0.083 and with the margin of error being +/- 0.007, was below the legal limit.

Normally, this is when an “expert” witness for the State will perform a miraculous extrapolation and explain how the defendant was much higher at the time of the stop. But the expert witness for the science was intellectually honest and said otherwise. When considering all the possibilities and giving estimates based on the time of arrest being both prior to or after peak alcohol absorption into the blood, the IFS opined the BAC at the time of arrest could even have been as low as 0.067 ± 0.01.

Dismissed for insufficient evidence. Extrapolation noted on Nolle.

Dismissed for insufficient evidence. Extrapolation noted on Nolle.

You have to give credit where credit is due…

“The court evaluating the reliability of a retrograde extrapolation should also consider (a) the length of time between the offense and the test(s) administered; (b) the number of tests given and the length of time between each test; and (c) whether, and if so, to what extent, any individual characteristics of the defendant were known to the expert in providing his extrapolation. These characteristics and behaviors might include, but are not limited to, the person’s weight and gender, the person’s typical drinking pattern and tolerance for alcohol, how much the person had to drink on the day or night in question, what the person drank, the duration of the drinking spree, the time of the last drink, and how much and what the person had to eat either before, during, or after the drinking.”

Mata v. State, 46 S.W.3d 902 (Tex. Crim. App. 2001)