KALAMAZOO, Mich. – A man accused of plowing his pickup truck into a group of Michigan bicyclists, killing five, was under the influence of drugs, a prosecutor said Wednesday as he added new charges.

Charles Pickett Jr. was already facing second-degree murder charges in the June 7 crash. The additional charges, driving while intoxicated causing death, are significant because they give a glimpse of what may have led to the tragedy on a two-lane rural road in Kalamazoo County.

Pickett, 50, heard the charges during what was supposed to be a routine hearing about schedules in the case. A not-guilty plea was entered.

Separately, a judge granted a request by defence lawyer Alan Koenig for a mental-health exam. The exam will determine whether Pickett understands the charges and can assist his attorney. It likely will put the case on hold for two months.

Outside court, county prosecutor Jeff Getting declined to describe the drugs that were discovered during toxicology tests by state police, only that they were “controlled substances.”

The National Transportation Safety Board is investigating the crash. Besides the five deaths, four bicyclists were injured.