PORTLAND, Ore. (AP) — A Milwaukie man who was arrested on suspicion of fatally hitting a pedestrian has been taken into custody again after officials said he assaulted a witness in the case.

The Oregonian/OregonLive reports Kevin Derrick was arrested Sept. 24 on suspicion of criminally negligent homicide and failing to perform the duties of a driver in the Sept. 19 death of 59-year-old Robert Keys, according to the Clackamas County Sheriff’s Office.

Authorities found Derrick’s car in Northeast Portland and he was booked into the Clackamas County Jail and later released on bail, officials said.

After his release, investigators said Derrick and his girlfriend, Alysha Esser, “confronted, physically assaulted and injured a witness in the case.”

The sheriff’s office said in a statement in a statement Wednesday it is believed the assault was intended to deter the witness from testifying against Derrick.

Derrick was arrested again and is again in jail, this time with bail of $1 million.

Authorities are searching for Esser, a 28-year-old Gresham resident, and officials said a felony warrant has been issued for her arrest.

It wasn’t immediately known if Derrick has a lawyer to comment on the case.