Memphis police officers are facing state charges including second-degree murder and aggravated assault in the beating death of Tyre Nichols.

Day four of the Tyre Nichols state trial began with the defense calling more witnesses. Preston Hemphill, a former officer, was first on the stand.

You can watch the trial live in the video box above. 3:25 p.m.: John Tisdale, an expert witness in police policy and use of force, was called to the stand by Tadarrius Bean’s attorney, John Keith Perry.