BATON ROUGE, La. (AP) - A defense attorney says a Louisiana man charged with killing three men and wounding a fourth may have been insane at the time of last year's string of shootings.

In a court filing Monday, one of Ryan Sharpe's lawyers asked a judge in Baton Rouge to order a mental examination for the suspect in the killings.

The attorney, Brent Stockstill, questions Sharpe's ability to assist in his defense.

The four shootings happened in a rural area north of Baton Rouge and left residents on edge for weeks. A law enforcement official told The Associated Press last year that Sharpe wasn't a suspect until he called the East Feliciana Parish Sheriff's Office and identified himself as the killer.

The official spoke only on condition of anonymity because the investigation was ongoing.