A witness in a murder case was beaten up after Hennepin County jailers mistakenly placed him in the same holding cell as the man he’d implicated.

Murder suspect Jonathan Nicholas “Thirsty” Turner was charged Thursday with tampering with a witness, a first-degree felony. That charge is atop first-degree murder charges he faces in two 2003 shootings.

Rondah Kinchlow, spokeswoman for the Hennepin County attorney’s office, said prosecutors “always” notify the jail when two prisoners shouldn’t be put together. But sheriff’s office spokeswoman Lisa Kiava said that didn’t happen.

“Jail staff had no information that these two inmates should have been kept separate,” she said. “We do have policy and practice in place that when we receive information that inmates should be kept separately, we do so.”

The criminal complaint against Turner, 24, does not name the beaten man and does not say why he was in jail, how he wound up in the same cell as Turner or how bad his injuries were.

Jailers stopped the beating within minutes.

An affidavit by Hennepin County sheriff’s Detective Bernie Bogenreif said the incident occurred March 4 when Turner was taken to a holding cell to await a morning court hearing.

He wrote that the two were mistakenly placed in the same cell after the witness had provided a taped statement implicating Turner in the killings.

The detective wrote that Turner had seen the state’s evidence against him and knew of the taped statement.

Turner faces a June trial on two counts of first-degree murder in the August 2003 killing of Javon Spencer, 19, of Minnetonka. Prosecutors say Spencer was a casualty of a turf war to decide which gang could sell drugs in a corner of the Phillips neighborhood.

Turner was convicted of the murder in November and sentenced to life plus five years. But in February, a judge threw out the conviction after both prosecutors and defense attorneys said one of the state’s trial witnesses actually was in jail when he claimed to have seen Turner shoot Spencer.

Hennepin County prosecutors re-indicted Turner in the Spencer case. He also faces charges of first-degree murder in the July 2003 shooting death of Marcus Julius Dortch, 24, of Minneapolis. Dortch was shot several times in the back as he fled two men with guns.

One witness told police that as the wounded Dortch lay on the ground, Turner stood over him and continued to pull the trigger of his pistol, even though the gun was empty.

Turner was scheduled for an 8 a.m. conference in the Spencer killing March 4, and that’s when he was placed in the cell with the witness.

Bogenreif wrote that a surveillance tape showed the attack.

The witness told Bogenreif that Turner had confronted him about “jumping on his case” as well as for his association with another witness who testified at Turner’s trial.

That man, known by the nickname “Lemon,” didn’t tell deputies what had happened but told his attorney once he got to court.

Bogenreif wrote that the account was corroborated by several other prisoners in the holding cell at the time of the attack.

Investigators also seized documents from Turner’s cell, and the detective wrote that “in those documents, the defendant states: ‘I just hit Lemon in his mouth for making a statement on me. That’s why I’m in the hole right now. I tried my best not to do it, but he betrayed me. I just couldn’t stand it. He sat there and lied to me and tried to put it on his kids. It was crazy.’ ”

The detective said they found other documents Turner allegedly wrote in which he “attempts to script testimony of other possible witnesses in advance of his murder trial.”

David Hanners can be reached at 612-338-6516.