Tai Chan, a former sheriff’s deputy for Santa Fe County, has twice been on trial for the alleged murder of another deputy, Jeremy Martin. Both trials ended with a hung jury, forcing the judge to declare a mistrial. Expert evidence played a significant role in the most recent prosecution and defense.

Facts of the Case

After transporting a prisoner from Santa Fe to Safford, Arizona, Chan and Martin checked into a hotel in Las Cruces. They spent the next several hours visiting drinking establishments. Witnesses who knew Chan testified that he and Martin were arguing in a tavern at about 10:00 p.m. on October 27, 2014. Chan told investigators that he jokingly told Martin that he could have prevented a double-homicide earlier in the year if he had arrived at the scene earlier.

Chan’s cousin drove Chan and Martin back to their hotel at about 11:00 p.m. According to Chan, Martin resumed the argument and told Chan that he was going to frame Chan for murder. Chan said that Martin pushed and kicked him during that altercation.

Chan left the room and called his girlfriend, who testified that Chan told her that he was being framed for murder. Chan seemed incoherent and the call terminated abruptly.

According to Chan, Martin found him outside the hotel. They walked back to their room together. Chan’s girlfriend called him again and Chan answered but did not speak. The girlfriend heard the two men arguing and then heard gunshots.

Chan testified that he was arguing with Martin when Martin grabbed a gun and threatened to shoot him. Chan tried to take the gun from Martin and a shot was fired. Chan then wrestled the gun away from Martin and began shooting at him. Martin fled and Chan chased him into the hallway, continuing to fire shorts.

Martin entered an elevator and descended to the lobby, where police officers found his “bullet-riddled body.” Five of the ten shots that Chan fired struck Martin.

Chan was charged with first-degree murder. His first trial began in May 2016. Chan testified that Martin was the aggressor and that he acted in self-defense. After about two weeks of testimony, the jury deadlocked and a mistrial was declared.

Forensic Investigation

Between the first and second trials, the lead investigator filed a lawsuit, alleging that she was denied adequate resources to investigate the case. She claimed that her superiors obstructed her investigation by denying access to a forensic investigator to help her examine evidence. The lawsuit alleged that the obstruction of her investigation was a form of retaliation because she reported sexual misconduct within the detectives’ unit at the Las Cruces Police Department.

The failure to investigate forensic evidence was evident during the first trial when both sides were surprised to learn that the blood-soaked sheet had never been tested for DNA. The test was only performed after the trial was underway. It revealed that the blood was Chan’s.

Chan’s attorneys asked the court to dismiss the case on the ground of outrageous misconduct because the police investigation had been obstructed and because witness testimony varied dramatically from the statements they allegedly made to the police. Chan’s motions challenging the integrity of the investigation were denied and Chan’s case proceeded to trial for a second time in May 2017.

Crime Scene Expert

At the second trial, the prosecution relied on a crime scene expert. Based on his reconstruction of the crime scene, Joseph Alan Foster testified that Chan and Martin struggled between the bed and a bathroom wall. He based that conclusion on the location of Chan’s dropped cellphone and blood on the sheets.

“The physical characteristics here are as if a battery is taking place — a blood-letting event,” Foster testified. Whether that testimony was more helpful to the prosecution or to Chan is unclear, since it tended to support Chan’s testimony that he fought Martin after Martin threatened him with a gun.

Foster testified that a bullet was fired from Chan’s gun and that the gun could have been three to six feet above the floor when the shot was fired. He could not say which of the two men fired the gun, although he acknowledged that the gun could have been fired while both of them were struggling to possess it.

Foster also acknowledged that Chan could have been in any of several different positions when the first shot was fired. After that, the forensic evidence suggested that he “repositioned himself” several times, which is consistent with Chan’s admission that he chased Martin. Based on a blood pattern analysis, Foster thought that one of the five bullets that struck Martin might have been fired while Martin was still in the room.

Psychology Expert

Testifying for the defense, police psychologist Philip Trompetter opined that Chan viewed Martin as a deadly threat. He based that opinion in part on a recording that a police officer made while interviewing Chan at the hotel.

Trompetter’s testimony may have helped the jury understand why Chan chased and kept shooting at Martin. Trompetter testified that police officers are trained to respond to deadly force by using their own deadly force and to keep shooting until the threat is dead. They fire many shots because they are not always certain whether any particular shot struck its target. Trompetter said that Chan’s actions were “consistent with the way officers would generally respond with a threat like that.”

Mistrial Declared

The second jury, like the first, was unable to reach a unanimous jury. The judge therefore declared another mistrial.

While there was some dispute about the votes cast by the deadlocked jury, it appears that by the final vote, no jurors were willing to convict of first-degree murder. The jurors may have been persuaded by expert testimony that Chan was responding to a threat and did not have a premeditated plan to kill Martin. Five of the twelve jurors apparently voted to convict Chan of second-degree murder.

The prosecution may be entitled to bring Chan to trial a third time, since double jeopardy does not protect him in the absence of an acquittal. At some point, repeated attempts to convict may persuade a judge that enough is enough and that due process can only be satisfied by dismissing the case.

In most cases, however, prosecutors conclude that if they could not get a conviction after two tries, there is no reason to believe they will fare any better in a third trial. Investing more resources in an unwinnable case is not a good use of public funds. Whether prosecutors will dismiss the case or seek a third trial has not yet been decided.