AUGUSTA – The 22-year-old Portland man accused of killing a cabdriver in Pittsfield has been admitted to a mental health facility after a judge found him incompetent to stand trial.

Derek Wilhelmsen, 22, was committed to the Augusta Mental Health Institute after a psychological examination this week, putting murder charges against him on hold indefinitely.

Wilhelmsen, who lived with his parents in Portland’s west end, took a cab to Pittsfield on Feb. 11. He later told investigators he was planning to kill his ex-girlfriend and her baby.

Instead, he repeatedly shot Nunzi Mancini, the cabdriver, in the back of the head. Wilhelmsen later told police that Mancini had called his ex-girlfriend a derogatory name.

The next day, Wilhelmsen was apprehended at a Portland counseling center after telling employees he was suicidal and had a gun at home.

Four years ago, Wilhelmsen was diagnosed with schizophrenia and was hospitalized at Jackson Brook Institute.

But M. Michaela Murphy, Wilhelmsen’s lawyer, said Thursday that her client has other psychological problems.

“There are some other neurological issues that make it a little more complex in his case besides schizophrenia,” she said.

The court-ordered psychological evaluation, conducted by a forensic psychologist hired by Murphy along with a state examiner, came after Justice Nancy Mills found Wilhelmsen incompetent to stand trial April 4.

Both evaluators found Wilhelmsen to be incompetent.

Wilhelmsen will remain at the Augusta facility until his condition improves enough that he can stand trial.

Murphy said it is not clear when court proceedings will resume.

If he is eventually released, Murphy anticipates entering a plea of not criminally responsible, Maine’s equivalent of not guilty by reason of insanity.

Deputy Attorney General William Stokes said a court finding a person incompetent to stand trial is uncommon, but not truly rare.

“Competency is a condition that can change,” Stokes said. “A person incompetent today can become competent through treatment and medication.”

If Wilhelmsen’s condition does not improve, the charges eventually will be dismissed and the state would move to have him committed to a psychiatric hospital.

“The court has an obligation, and so do we, to make sure we’re not trying a person for a crime when that person is incapable of defending himself,” Stokes said.

Wilhelmsen had been held without bail at the Somerset County Jail until Tuesday, when he was transferred to the psychiatric facility.