Parkland, Wash. ? A man with an extensive criminal past — including a lengthy prison sentence commuted by former Arkansas Gov. Mike Huckabee nearly a decade ago — was being sought Sunday in a deadly ambush on four police officers who were gunned down inside a coffee shop.

Pierce County Sheriff’s spokesman Ed Troyer told reporters that Maurice Clemmons, 37, was believed to have been in the area around the time of the shooting, but declined to say what evidence might link him to the shooting.

Clemmons has an extensive violent criminal history from Arkansas, including aggravated robbery and theft, the sheriff’s office said. He also recently was arrested and charged in Washington state for assaulting a police officer, and second-degree rape of a child. Using a bail bondsman, he posted $150,000 and was released from jail last week.

Still unclear was why a man entered the coffee shop and gunned down Sgt. Mark Renninger, 39; and Officers Ronald Owens, 37; Tina Griswold, 40; and Greg Richards 42.

“We have no motive at all,” Troyer said. “I don’t think when we find out what it is, it will be anything that makes any sense or be worth it.”

The four officers were with the 100-member police department of Lakewood, which adjoins the unincorporated area of Parkland, where the shootings took place.

Richards’ sister-in-law, Melanie Burwell, called the shooting “senseless.”

“He didn’t have a mean bone in his body,” she said. “If there were more people in the world like Greg, things like this wouldn’t happen.

An impromptu memorial of an American flag, flowers and candles decorated the front yard at Renninger’s home. His family declined to speak with reporters.

On Sunday night, a motorcade of dozens of police cars and motorcycles with lights flashing escorted the bodies of the four officers to the medical examiner’s office.

Troyer said investigators believe two of the officers were killed while sitting in the shop, and a third was shot dead after standing up. The fourth apparently “gave up a good fight.”