BUTLER TWP — A Connoquenessing Township man has pleaded guilty to causing a fatal vehicle collision while impaired by drugs.

As part of a plea arrangement this week with the Butler County District Attorney’s Office, Justin Enslen, 26, will likely face 5 to 10 years in state prison when he is sentenced March 20.

According to court records, Enslen was high on a heroin, morphine, methadone, marijuana and a prescription antiseizure drug when he drove home from his regular visit to a methadone clinic on Feb. 18, 2013. Methadone is a prescription commonly used to treat heroin addiction.

Enslen, who did not have a driver’s license, crossed over the center line on Route 68 in front of an elementary school in Connoquenessing Township.

Enslen’s Dodge Ram pickup collided head-on with a Nissan Frontier driven by Mark Bishop, 52, of Oakland Township. Bishop, who was on his way to the auto show in Pittsburgh, was killed.

Enslen and Bishop’s sister and front-seat passenger, Holly Merkner of Lyndora, were injured.

Enslen pleaded guilty to homicide by vehicle while driving under the influence and driving with a suspended license.

Neither Enslen’s defense attorney Terri Schultz nor the prosecutor, Assistant District Attorney Richard Bosco, could be reached for comment.

Enslen at the same time also pleaded guilty to smuggling drugs into the prison.

Enslen and other inmates were allegedly hiding Suboxone, a drug used to treat opioid addiction, in the seams of envelopes that were mailed to the inmates.

In that case, Enslen pleaded guilty to conspiracy to possess contraband. The sentence negotiated as part of a plea arrangement in that case, 3 to 6 years, would run at the same time as the homicide sentence.

Assistant District Attorney Mark Lope, who prosecuted the contraband case, declined to comment.