The Tarrant County District Attorney’s digital forensics services began 15 years ago with one investigator who programmed one computer to analyze data in economic crimes cases.
As cellphones and other digital devices grew more widespread, so did their usefulness in criminal cases, leading former district attorneys Tim Curry and Joe Shannon to add more staff to analyze data from video and audio equipment, cellphones and cameras.
But the investigators and forensic analysts were scattered among several offices until May when the five-member Digital & Forensics Services team moved to a new “one stop shop” in the Tarrant County Plaza Building across from the Tim Curry Justice Center.
District Attorney Sharen Wilson, who took office in January, said the move will enable the consolidated unit to provide even more digital forensic services to Tarrant County and other jurisdictions than it been quietly performing for years.
“Tim Curry recognized the need to begin investing in this area years before many others,” Wilson said in a statement. “By continuing to stay ahead of the curve, the citizens of Tarrant County now own a digital forensic and technology facility that is able to give critical assistance not only to law enforcement agencies in Tarrant County but agencies across the state and around the country.”
As the only “one stop shop” for digital media in Texas, the Tarrant County unit members have assisted more than 60 law enforcement agencies the past three years in addition to the 40 Tarrant county police departments.
Mark Porter, one of the county’s two certified forensic video analysts, provided video analysis for Kaufman County prosecutors in the capital murder trial of Eric Williams, sentenced to death last December for the 2013 murders of District Attorney Mike McLelland and his wife Cynthia McLelland.
“I processed substantial video to put in a time line (for the murders),” said Porter, whose video analysis unit was put together in 2006 with grants from the Association of Police Chiefs.
Investigator Kyle Gibson, the unit’s computer forensics examiner, said he has testified in trials in Johnson and Hood counties as well as Tarrant County.
Gibson said the new facility – which has “breakdown stations” to remove computer hard drives, four computer examining stations and room for four more – will enable him to process even more computer data.
He said he is now working about 60 separate cases, some with multiple computers. When new cases come in, other cases often are set aside to work on the breaking cases.
The most recent example, Gibson said, was the kidnapping of a Benbrook girl, which led to the fatal shooting by police of her uncle in Louisiana and the girl’s safe return to her parents.
“We know the value of what we can find in a computer and phone,” he said. “It’s not necessarily the smoking gun but it can be the last little piece in a puzzle.”
In certain cases, such as child pornography, computer analysis can be the crucial piece of evidence, said Marty Purselley, chief of the special victims division, which prosecutes crimes against children and elder abuse.
Purselley, who was handling computer crime cases before there was a digital forensics unit, said most child pornography cases are circumstantial. The suspect rarely confesses and is usually not caught red-handed viewing pornography on a computer, he said.
“The ability to narrow it down to one person is incredibly helpful,” Purselley said. “The context of that image, what is going on that computer, is everything. That’s what digital forensics gives us. They provide the context of a lot of bad acts.”
Christy Jack, a Tarrant County prosecutor for 24 years before leaving for private practice this year, goes further. She sees digital forensics as crucial to many cases. And jurors raised in a digital age have come to expect that type of evidence, she said.
Jack cited the 2012 capital murder trial of Mark David Soliz, accused of a five-day crime spree that led to the murder of an elderly Johnson County woman and a Fort Worth deliveryman.
Jack teamed up with Johnson County prosecutors to try Soliz for the death of Nancy Weatherly. After Soliz was convicted of capital murder, prosecutors presented video evidence of the events surrounding the murder of Ruben Martinez. Jack believes that evidence led to his death sentence.
“Analysis of the video footage from the store where the victim was making a delivery placed the defendant’s car at the scene of the crime moments beforehand,” Jack said. “It showed the direction from which the shooter and his accomplice came.
“It illuminated the attire worn by the shooter. It demonstrated the length of time the shooter laid in wait for the unsuspecting victim. And it pinpointed the time the shots were fired. That’s a prime example of how digital evidence brought to the jury solidified our argument that Soliz was deserving of the death penalty.”
The value of digital forensics in criminal cases cannot be overstated, she said.
“You can’t try a case without it these days,” Jack said. “Juries expect it and they have a right to.”
Digital forensic files
While many high profile trials are played out on television and newspapers, the digital forensic evidence that is becoming part of those trials has received little notice.
That may change with the opening of a new Digital Forensic and Technical Services unit, consolidated from staff previously scattered in different units.
Investigators and forensic analysts cited several cases that used digital forensics:
John Hummel, tried for the 2009 murders of his pregnant wife, father-in-law and 5-year-old daughter, was sentenced to death in part due to forensic evidence obtained from his work computer, said Assistant Chief Investigator Danny McCormick.
While Hummel stabbed and beat his family to death, a computer examination showed that he had researched the effect of rat poison on humans and had an online profile on a dating site.
The forensic staff also used surveillance videos from several locations to document Hummel’s movements before and after the murders.
After the 2013 sexual assault and murder of 6-year-old Alanna Gallagher, forensic analysts worked with Saginaw police to process surveillance video, computers and cellphones as various suspects were interviewed.
Ultimately, Saginaw teen Tyler Holder pleaded guilty and was sentenced to life in prison for the girl’s murder plus 40 years for the attempted murder of a police officer shot in the head while attempting to arrest him.
In 2011, Rodney Ricketts committed dozens of burglaries across Tarrant, Denton, Dallas and Collin counties. After his arrest during a Bedford burglary, Ricketts was tried using forensic evidence from surveillance cameras and computers. He was convicted by a Tarrant County jury, which assessed a 49-year prison term. – Martha Deller