Brendan O’Brien & Joseph Ax

(Reuters) – The parents of a Michigan teenager who shot and killed four schoolmates earlier in the week are likely to be charged by prosecutors on Friday.

Ethan Crumbley is a senior at Oxford High School, about 40 miles (60km) north Detroit. He faces multiple charges, including murder. After Wednesday’s arraignment, Crumbley was released without bail. As an adult, he has been indicted.

A news briefing has been scheduled by county prosecutors for Friday at noon EST (1700 GMT), to give an update about the investigation.

The parents James Crumbley and Jennifer Crumbley were not immediately aware of the possible charges they could be facing. Karen McDonald from the Oxford County Prosecuting Office has stated that she will be charging them. She also suggested that their son was negligent for having access to the gun.

Michigan is not like other states that require gun owners to protect their firearms from children.

According to authorities, James Crumbley bought the semi-automatic pistol four days prior to the shooting that left six victims and one teacher injured.

In connection with school shootings, parents are seldom charged.

Education Week reported that the attack was the worst school shooting in the country this year. This is the latest of a series of mass shootings at U.S. public schools dating back decades.

Investigators believe the attack was premeditated. They cite videos Crumbley had recorded that night in which he spoke about shooting students. Also, they cite a journal he kept from his backpack, where he described his plans to kill classmates.

According to Oakland County Sheriff Michael Bouchard, Crumbley had either the gun in his bag or kept it somewhere else on school grounds. This was based upon an analysis of video footage from school that proved Crumbley never left the school after arriving on that day.

Bouchard earlier this week stated that Crumbley was the victim of a school shooting and that officials from the school met with his parents to discuss behavior in class that they considered concerning.