04/06/2015 11:30 EDT | Updated 06/06/2015 01:12 EDT

Doctor testifies on PCP; 1st defence witness in murder trial of ex-NFL player Aaron Hernandez

FALL RIVER, Mass. - The first defence witness in the murder trial of former New England Patriots player Aaron Hernandez is a doctor who says PCP can cause people to be suddenly violent, even days after smoking it.Hernandez's attorneys on Monday focused on the drug, which Hernandez's two co-defendants were seen smoking two days before the June 2013 shooting death of Odin Lloyd. Lloyd was dating the sister of Hernandez's fiancee.During cross-examination, prosecutor Patrick Bomberg showed Dr. David Greenblatt a video of the men from three minutes after the killing. Greenblatt acknowledged he could not tell if they were under the influence of PCP.The defence has said it plans to call two more witnesses, then rest its case.The judge has said she expects closing arguments to be delivered Tuesday or Wednesday.