MISSOULA, Mont. -

NBC Montana wanted to learn more about the correlation between violence and drugs after a Washington man admitted killing his son near Anaconda.

Jeremy Cramer has pleaded guilty to deliberate homicide in the death of his 3-year-old son in July.

Witnesses remember Cramer acting erratic by jumping in front of traffic east of Anaconda before entering a convenience store covered in blood.

Investigators said he may have taken a high amount of the stimulant drug Adderall, leading up to his little boy's death.

Erin Corbett is a licensed addictions counselor. She said heavy drug use can cause paranoia, which can lead to violence.

"There's a possibility for violence and other medical issues," said Corbett, "substance abuse and psychosis."

Cramer's brother told police Jeremy had been a methamphetamine user. There is nothing public that links Cramer to any mental illness. But the courts are filled with cases.

North of Missoula, Nathan Lee William Calvert murdered Doug Morigeau, and tried to kill Morigeau's wife. In November, Calvert pleaded guilty but told the court he smoked synthetic marijuana, and wasn't taking his medicine for his mental illness the night of the crime.

"When people have the mental health issue, and then add drugs," said Corbett, "this definitely increases for having violence perpetuate."

Corbett is the clinical coordinator for Community Medical Services for Montana. Drug addicts can get treatment here. Corbett said its chairs are often filled with clients, and more all the time.

"We have a population in Missoula of 200," said Corbett, "our clinic in Kalispell has 250 clients, we have a new clinic in Billings with 100 clients, and we're bursting at the seams."

Corbett said many are coming from out of state, especially Washington and California.

The industry calls that Greyhound Therapy, a last ditch effort to relocate clients to more rural areas.

But the addictions counselor said rural services are extremely limited.