The Biddeford man charged with criminal speed and carrying a concealed weapon during a weekend traffic stop on the Maine Turnpike now faces federal charges of possessing guns while using illegal drugs and lying about it to buy another gun.

Timothy Courtois, 49, was arrested Sunday after driving 112 mph on I-95 South, police said. When stopped, police found he had an assault rifle, a shotgun and several semi-automatic handguns. Courtois allegedly told Maine State Police when he was stopped that he was on his way to Derry, N.H., to kill a former employer. He also had newspaper clippings of the Colorado theater shooting from Friday and claimed to have gone to a showing of “The Dark Knight Rises” in Saco with a loaded gun.

Courtois had a pipe and some synthetic marijuana and admitted to investigators that he liked to smoke marijuana and synthetic versions of it, police said.

Under federal law, users of illegal drugs are prohibited from owning guns.

If convicted, Courtois faces a maximum prison sentence of 10 years and a fine of up to $250,000 on each of three charges. Courtois is being held at York County Jail and his appearance in federal court has not been set.

According to an affidavit filed by a special agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives, Courtois also lied on the form he filled out Friday at Cabela’s when he bought a DPMS/Panther Arms, Model A-15, .223 caliber rifle. Courtois checked the form saying he was not a user of illegal drugs.

An indication of his mental state, the ATF agent’s statement said Courtois told investigators that he was going to Derry to attend an Alcoholics Anonymous meeting – though he didn’t drink – and that he asked them to buy him some marijuana so he could smoke and eat Chinese food.

Family members say what Courtois actually did and intended to do is a mystery because he is suffering from mental illness. His condition has historically been treated with medication but he recently stopped taking it, family members and co-workers said.

Although Courtois has had a history of mental illness, he was never violent, according to a family member.

However, he has had a few psychotic episodes when he has stopped taking his medication, said his brother Cory Courtois.

“He has a diagnosed mental condition,” said Cory Courtois, who said he believes his brother suffers from bipolar disorder and manic depression. “When he was on medication, he had a normal life.”

Cory Courtois said family members have been trying for a couple weeks to get his older brother help, but they and police were unable to force him to go to the hospital and get treatment since he had not threatened himself or anybody else.

Police also were unable to confiscate his guns because he had not broken any laws or done anything that would allow them to take them.

Cory Courtois said the family was frustrated by the inability of police to intervene in recent weeks as his brother’s condition worsened without his medication.

“They said there’s really nothing they could do. Their hands were tied,” he said. “Without the intent of harm, there was nothing they could do except to unfortunately wait for something else to happen.”