A jailed Oregon man accused of kidnapping a woman in Seattle and locking her in a cinder block cell until she broke the door to escape has unsuccessfully tried to break out of his own cell, authorities said Friday.

Negasi Zuberi, 29, attempted to smash through his cell window at Jackson County Jail on Tuesday, the Jackson County Sheriff’s Office said in a statement.

The facility’s exterior windows are made of reinforced glass, and Zuberi was only able to damage the interior layer, according to the statement. He now faces added charges of attempted escape and disorderly conduct.

The office of one of Zuberi’s attorneys, Devin Huseby, declined to comment on the new charges Friday. A message left for another of his lawyers wasn’t immediately returned.

According to the sheriff’s office, a maintenance worker heard a suspicious noise coming from inside one of the cells Tuesday afternoon. Jail deputies found Zuberi standing on his bunk bed near the chipped window, according to the sheriff’s office statement.

Deputies found what they described as an improvised tool that they believe Zuberi used. He has since been moved to a cell with no exterior windows, officials said.

On July 15, Zuberi solicited a woman to engage in prostitution along Aurora Avenue in Seattle, authorities say. Then he allegedly told the woman he was an undercover officer, showed her a badge, pointed a stun gun at her and placed her in handcuffs and leg irons before putting her in the back of his vehicle.

He then drove hundreds of miles to his home in Klamath Falls, Oregon, and locked the woman in a cinder block cell, according to the FBI. After the woman escaped, Zuberi fled and was arrested by state police in Reno, Nevada, on July 16.

Zuberi, who authorities say has used the aliases Justin Hyche, Justin Kouassi and Negasi Sakima, has pleaded not guilty to charges of interstate kidnapping and transporting an individual across state lines with intent to engage in criminal sexual activity. He could face up to life in prison if convicted.

The FBI said it was looking for additional victims dating back to 2016 after linking him to violent sexual assaults in other states.