MEMPHIS, Tenn. -- The federal trial for three former Memphis Police officers charged in the beating death of Tyre Nichols is capping off its third week with testimony from witnesses in the defense's case. The prosecution rested on Thursday and the defense called their first witnesses to the stand. Stephen Leffler, one of Demetrius Haley's lawyers called on Forensic Biology Expert Samantha Spencer, a former Tennessee Bureau of Investigation Special Agent Forensic Scientist. Tyre Nichols trial: Prosecution rests, defense begins its case Spencer said testing done on Demetrius Haley and Emmitt Martin's boots, which were taken by the TBI the night of the Tyre Nichols beating, revealed Tyre Nichols' DNA. On Friday morning, use-of-force expert witness John Tisdale was called to the stand, hired by Tadarrius Bean's legal team. Tisdale is a former Chief of Police in Gallatin, Tennessee, and Parker, Arizona. He also previously worked in Jackson, Mississippi. He watched body camera and Skycop footage and analyzed the baton strikes and kicks to Tyre Nichols, comparing those to MPD's Use-of-Force Policy and also national policy standards. Earlier in the trial, a trainer at the MPD academy presented a list of hours and classes required for MPD officers to graduate. On that list are four hours of handcuffing and using the police baton. Tisdale mentioned in his testimony that officers need more than four hours of training in those areas. He also testified that once a medical team arrives on a scene, officers need to get out of the way, and are not required to tell EMTs anything unless they are asked. Bean's attorney, John Keith Perry, asked Tisdale what would happen if a person like Officer Bean did not get out of his vehicle to respond to a dispatch call after he learned about it and encountered the suspect. "He wouldn't work for me anymore," said Tisdale. "If you don't go after the suspect and at least try, you show no value." John Tisdale Prosecutors questioned Tisdale on how he got involved in the case, and Tisdale stated that he was paid $14,000 for his work. Tisdale confirmed to prosecutors that officers can not use force if they are angry or mad, and it would be wrong for an officer to encourage another officer to use force. But, he ended his testimony by stating that what he saw Bean specifically doing on the video, was not against MPD policy. The Tennessean reported in a 2014 article that John Tisdale resigned from his position as Chief of Police in Gallatin, Tenn. after an investigation by the TBI into Tisdale's alleged misuse of a criminal history database. Next up on the witness stand was a former MPD officer and character witness who described himself as a "very close" friend of Tadarrius Bean — Bryant McKinney. McKinney said he went through the police academy and graduated with Bean. He described Bean as humble, kind, a "true servant leader," and always putting others before himself. McKinney also claimed Bean is the type of person who is "by the book" with “no loopholes.” Prosecutors asked if putting others before yourself is the quality of someone who doesn’t help in a medical emergency, doesn’t tell medical providers about head trauma, and uses excessive force. Garrett O'Brien, a former Memphis Police Officer and MPD trainer, testified on behalf of Justin Smith. O'Brien told the jury that "hammer blows" and "palm strikes" are taught in the academy. hammer blows, which O'Brien said are within MPD policy, was demonstrated as closed fist punches at a downward angle to the head. He also testified that deadly force should only be used when the suspect's resistance calls for deadly force, noting that force and resistance should be equal. O'Brien was part of an investigation into police use of force by the Institute for Public Service Reporting in 2021. Don Cameron, a longtime California-based police trainer, was called to the stand by Demetrius Haley's counsel. Attorney Michael Stengel asked Cameron hypothetical questions regarding what would and would not be considered an appropriate use of force. He stated that if a suspect is feeding from the officer and actively resisting, a kick issued to the torso, which the defense is claiming took place, would be justified. When asked if the force used on a suspect should be equal to the resistance from the suspect, Cameron agreed. But, when the prosecution asked if a kick to the head would be considered deadly force, Cameron answered, "If it killed a person, yes." Court adjourned around 4:30 p.m. Friday evening. The trial will pick back up on Monday morning with additional witnesses from the defense.