They continued to aggressively try and cast doubt on the state's argument that Allen murdered Libby German and Abby Williams.
The girls were found dead with their throats slit near the Monon High Bridge in Delphi, Indiana back in February 2017.
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Betsy Blair was the first witness called to the stand. She testified earlier that she was on the trail leading to the bridge multiple times on the day of the murders.
Blair said she saw one vehicle near the trail; it was backed into the area near the old Child Protective Services building. She said it stuck out to her because it was "not parked how other people park."
Blair described the vehicle as a four-door sedan; she couldn't remember exactly what color it was, but she said it wasn't brightly colored. She also described the car as an older model vehicle.
The state says they believe Allen drove his 2016 black Ford Focus to the trail the day of the murders.
A juror asked Blair if she thought the car could've belonged to someone working at the CPS building, Blair said the building looked abandoned.
The defense also called Dr. Stuart Grassian. He is s a psychiatrist who specializes in solitary confinement, false memories, and false confessions.
Grassian listened to Allen's calls from prison and read transcripts from other inmates.
He told the court, when people are held in solitary confinement for a long period of time, they can become "confused, disoriented" and "extremely lonely" since there is minimal opportunities for stimulation.
Grassian said he never visited Allen's cell but saw video provided by the defense.
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Defense attorney Brad Rozzi asked Grassian if he noticed symptoms of delirium on Allen's phone calls to other people, Grassian responded, "Absolutely yes."
Grassian went on to say, "Your memory can shift over time." He added this was "perfectly consistent" with Allen's symptoms.
The jury asked Grassian several questions. One was if psychotic behavior can go back to normal after the person is removed from a situation?
Grassian responded, "Generally, yes."
Another juror asked Grassian if he believes someone described as normal can become psychotic after six months? Grassian said, "Absolutely. I've seen it happen."
The defense then called Dr. Erin Warren to the stand. He owns a business dealing with crime scene reconstruction and worked for the Tennessee Bureau of Investigations in the firearm identification unit.
The defense asked Warren to review the work of Melissa Oberg. She is the former Indiana State Police crime lab technician who examined the unspent round found at the murder scene and compared it to Allen's gun.
Oberg's analysis found the crime scene round had been cycled through Allen's gun.
This is the state's key piece of evidence tying Allen to Libby and Abby's deaths.
Warren reviewed the results of ISP testing, and he told the jury he considered them to be an "apples to oranges" comparison. He said he came to this conclusion because Oberg compared the initial round, which had been cycled, not fired, to a bullet fired from Allen's gun.
When Oberg was on the stand, she told the court an "ejector mark was an ejector mark" regardless of whether a round was cycled or fired.
Warren disputed that testimony saying the lab needed to identify toolmarks under the same conditions in which the bullet was found.
Jurors had 15 questions for Warren about the testing method on the cartridge, which was notably more questions than most witnesses have gotten from the jury.
Allen's defense team continued to call technical experts to the stand on Tuesday afternoon
Former FBI forensic examiner Stacy Eldridge was the defense's 21st witness to testify. She told the court she spent 65 hours going over digital information in the case.
Eldridge said she examined the data taken from German's cellphone, as well as reports and depositions on other data pulls.
Eldridge's testimony agreed with several aspects of what state police experts said they found. She did criticize investigators for not doing a better job of extracting data from German's phone, which could have led to better findings.
One major disagreement Eldridge told jurors about was when German's phone last connected to service and received messages.
Eldridge said her analysis showed the phone last connected to a tower at 5:44 p.m. on Feb. 13, 2017. The phone then connected again at 4:33 a.m. on Feb. 14th. This is when police said German's phone received several messages sent 12 hours before.
Eldridge told the court after 5:44 p.m. the phone attempted to reconnect to the tower, but no data was being used by any apps between 5:44 p.m. and 4:33 a.m.
The defense team asked if Eldridge could provide an explanation for why the phone stopped receiving signal. Eldridge responded by saying she had no explanation outside of movement of the phone or the signal being blocked.
The biggest moment of her testimony came when Eldridge said at 5:45 p.m. on Feb. 13, 2017, a phone call came into Libby's phone and within "milliseconds" a headphone jack was inserted.
Eldridge went on to say the headphone jack was removed nearly five hours later at 10:32 p.m. She said, "I cannot think of any explanation that doesn't involve human interaction."
During cross-examination, the state asked Eldridge about the service around the Monon High Bridge. She said she didn't know, and its possible German's phone wasn't connected because it was going in and out of service.
Prosecutor Nick McLeland asked if plugging in a headphone would have made the phone log a movement.
Elridge responded, "It could; it could not."
He followed up by asking if the phone would log movement if it was picked up and carried through the woods. She answered, "Yes."
Eldridge also conceded there was no data to show the phone was ever turned off.
Jurors had several questions including if Eldridge ever created her own timeline using the data from German's phone. She answered, "no."
Another juror asked if Eldridge could tell if the phone was on silent or vibrate. She said she didn't know.
Eldridge was then asked if water or moisture on the phone could register as movement.
She also said she did not know.
State police experts Brian Bunner and Chris Cecil were called back to the stand. The defense pressed them on their lack of reporting about the headphone jack data.
Cecil responded by saying he Googled the jurors' question about water or moisture on the phone. He said he read a headphone jack could register as being used if water or dirt is in the port.
The defense quickly countered by asking Cecil, "Do you normally Google search when conducting research in a criminal investigation?"
Cecil responded with "not normally, no." He said normally he uses peer-reviewed research.
Defense attorney Jennifer Auger then pressed further by saying, "You and the state have had seven-and-a-half years to research?"
Cecil responded, "That's correct."
Auger then said, "and you came in here with a Google search?"
Cecil said, "That's correct."