Updated

Prosecutors claim the suspect in the deadly Tucson shooting rampage needs another eight months of mental health treatment at a federal prison facility in Missouri, but lawyers for Jared Lee Loughner asked a federal court Friday to deny any extension.

Loughner's attorneys said prosecutors have failed to establish "clear and convincing evidence" that there's substantial probability his mental condition can be improved so a trial can proceed. They also asked for an evidentiary hearing to "determine the legal and factual sufficiency" of the request to extend Loughner's commitment.

Loughner, 23, has been held in a facility in Springfield, Mo., since May 27 after being declared mentally unfit to stand trial.

He has pleaded not guilty to 49 charges in the Jan. 8 shooting that killed six and wounded 13, including U.S. Rep. Gabrielle Giffords.

Loughner's evaluation period at the prison is scheduled to end Sept. 26.

Earlier this month, prosecutors were seeking to extend Loughner's treatment by four months — through Jan. 26.

But on Friday, prosecutors said a psychologist at the Missouri prison believes "there is substantial probability that within eight months, the defendant will be made competent" and asked a federal judge to order that Loughner "be committed for an additional eight months."

Mental health experts have determined Loughner suffers from schizophrenia and he's been forcibly medicated with psychotropic drugs at times while in Missouri despite his lawyers' objections.

Prison officials concluded Loughner's psychological condition was deteriorating, noting that he had been pacing in circles near his cell door, screaming loudly and crying for hours at a time.

Loughner's attorneys said their client is not getting better while at the Missouri facility "and is so disabled that he has been on a suicide watch since early July."

"And, even after some 60 contiguous days of anti-psychotic medications, he continues to be psychotic," Judy Clarke, Loughner's lead attorney, said in her filing Friday. "He is now also severely depressed, tearful, restless, agitated and psychotic."

Clarke said the forced medication "has done nothing to affect his delusions or the very prominent cognitive deficits, severe thought disorder or negative symptoms which are the hallmarks of Mr. Loughner's schizophrenia and all of which directly affect his ability to stand trial."

Prosecutors also want Loughner to appear in person Wednesday at U.S. District Court in Tucson for a hearing on the extended treatment rather than via video teleconference from San Diego. There was no immediate response Friday from Loughner's attorneys on the request to have him transported to Tucson and no immediate ruling from a federal judge.