A former Phoenix police officer accused of murder could take the stand this week to defend his actions.
Richard Chrisman's defense attorney called its first witness on Monday.
Attorney Craig Mehrens said Chrisman will take the stand in his own defense.
On Monday, jurors heard from Norman Wade, a toxicologist with the Maricopa County Medical Examiner's Office, who told jurors the victim, Daniel Rodriguez, had meth in his system.
Wade said meth use can lead to anxiety, hyperactivity, and aggressive and bizarre behavior.
The most heated moment in court happened outside the presence of the jury between Mehrens and prosecutor Juan Martinez.
Each attorney took a jab at each other over who is paying for their services.
Martinez claimed the Phoenix Law Enforcement Association is paying Mehrens to defend Chrisman and claimed a witness on the stand had connections with the group.
Mehrens denied the claim and then complained taxpayers, including him, are left to pay for Martinez's services.
Chrisman and his partner on the call, Sergio Virgillo, are the only two witnesses alive to tell what happened inside the home when Chrisman shot and killed the victim.
Chrisman claims he shot Rodriguez because Chrisman feared for his safety.
Earlier this month, Virgillo testified Chrisman basically executed the victim.