(CNN) The man suspected of fatally shooting three people in a racially motivated rampage in Fresno, California, will undergo a mental competency evaluation, according to Steve Wright, assistant district attorney for Fresno County.

Kori Ali Muhammad, 39, was to be arraigned Friday on charges of murder and attempted murder, but the arraignment was delayed pending the test.

Muhammad was arrested Tuesday after killing three men at random, Fresno police Chief Jerry Dyer said. Muhammad, who is black, acted out of racial hatred against white people, Dyer said.

"He said he did not like white men, and that white people were responsible for keeping the black people down," Dyer said

The investigation into those three killings is ongoing, the Fresno County district attorney's office said. No charges have been filed.

Friday's arraignment involved another fatal shooting that happened last week. Muhammad is accused of shooting and killing 25-year-old unarmed security guard Carl Williams III and attempting to shoot a second security guard in the parking lot of a Motel 6 in Fresno on April 13.

Eric Christensen, Muhammad's public defense attorney, told CNN he requested the mental health evaluation after a brief initial meeting with Muhammad, moments before Friday's scheduled arraignment.

Christensen said he had grave concerns about Muhammad's mental competence after speaking with him for about five minutes.

Three dead in less than 2 minutes

Officials said Muhammad hid out from police for days after the guard's shooting until he saw a photo of himself on the news as a suspect. Police said he then decided to act on his hatred of white people.

"What he told our detectives last night was that once he saw that he was wanted for murder, he was not going to go down for shooting a security guard for disrespecting him -- but that he was going to kill as many white males as possible," Dyer said Wednesday.

"And that's what he set out to do."

Police said Muhammad went to Fresno's Tower District and shot and killed three white men in a span of less than two minutes.

Muhammad then surrendered to police, authorities said.

Suspect's background

Muhammad was indicted in 2005 on charges of possession with intent to distribute cocaine and possession of two rifles and a semi-automatic handgun, according to federal court documents.

After a psychiatric evaluation, he was found not competent to stand trial in July 2005.

His public defender at the time raised questions about whether Muhammad was mentally fit to stand trial, according to court records. He "appeared eccentric with some bizarre beliefs" and appeared to have hallucinations, and he had at least two mental health hospitalizations, court records show.

In June 2006, Muhammad was found competent to stand trial. He pleaded guilty and was sentenced to 110 months in prison, which was later reduced to 92 months.