Prosecutors say the suspect who allegedly beheaded a co-worker at a Moore, Oklahoma, food processing plant should have been in prison longer. Alton Alexander Nolen, 30, had served just two years of a six-year drug sentence.

Nolen was expected to be charged Monday with murder for Friday's incident at Vaughan Foods.

Oklahoma County District Attorney David Prater told the Oklahoman prosecutors "have no idea" how long someone will serve once convicted unless the individual is convicted of a violent crime.

"This case perfectly illustrates the problem with the Department of Corrections," Prater said.

“You’d think there would be, maybe, some sort of screening process or something that could have identified some of these issues while he was [in prison],” Cleveland County District Attorney Greg Mashburn said. “Maybe it wouldn’t have caught it. Maybe it would have. Clearly, he needed to be in prison."

Nolen allegedly took out his anger at being fired on two co-workers, one of whom was beheaded and the other slashed. Killed was Colleen Hufford, 54, whose home was destroyed in the Moore tornado a year ago. Traci Johnson, 43, of Oklahoma City was injured.

Before the incident, Nolen posted on his Facebook page pictures of beheadings and wrote: “Islam will dominate the world. Freedom can go to hell.”

He was shot by police and hospitalized but is expected to recover, the Oklahoman said.

Nolen, a Muslim convert who goes by Jah’Keem Yisrael on Facebook, was convicted in March 2011 on charges of marijuana possession and assaulting a state trooper. The following month, he was sentenced to six years for cocaine possession. The three sentences ran concurrently even though the convictions were in different counties. With credit for good conduct and time spent in jail before conviction, time served was reduced.

Nolen's mother and sister posted a video on Facebook in which they defended the suspect.

"What they say Alton has done, I want to apologize to both families. … I'm praying justice will prevail. The whole story will come out," his mother said.

A longtime friend of Nolen's said the suspect was raised as a Baptist and is shocked by the accusations.

"It hurts me," Ricky Kennybrew, 27, told the Oklahoman. "I cannot see him doing anything like that unless there was more to it."

Kennybrew also said he was surprised his friend decided to convert to Islam.