(CNN) Arriving on the scene of a double slaying last month, Phoenix police took a man -- the son of one of the victims -- into custody, not knowing they were handcuffing a suspected serial killer.

Officers felt Cleophus Cooksey was acting strangely, perhaps trying to conceal something. They arrested him in the December 17 deaths of his mother, Rene Cooksey, and his stepfather, Edward Nunn, but that was just the beginning of a multi-jurisdiction investigation, Phoenix Police Chief Jeri Williams said.

"Phoenix police officers arrested Cooksey on scene and he's been in jail since, but our detectives didn't stop there," Williams said. "They kept digging because that's what good police officers do."

Cooksey, 35, would soon be linked to seven more killings over a three-week period in the Phoenix metro area.

Using technology for forensics analysis, investigators soon linked Cooksey to a total of nine killings in Phoenix, Glendale and Avondale, the chief said, appearing alongside police chiefs from those cities, as well as agents from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives.

A decision on what charges Cooksey will face should come in the next few weeks, said spokeswoman Amanda Jacinto of the Maricopa County Attorney's Office.

Cooksey was indicted last month on two counts of first-degree murder and a count of possession of a weapon by a prohibited person, according to online court records. Those charges are related to the December 17 killings.

Public defender Gary Beren, who is listed as Cooksey's lawyer in the December 17 killing, could not be immediately reached for comment.

A music producer who worked with Cooksey, an aspiring rapper, said he remembered the accused killer as quiet and positive. He seemed like "a spiritual guy," Jeremy Daniel said.

The nine killings

This police handout provides the timeline of Cooksey's alleged crimes.

The killing spree began November 27 when police found the bodies of two men -- identified as Andrew Remillard and Parker Smith -- in Phoenix, police said. Evidence at the scene pointed to Cooksey, Williams said.

On December 2, Cooksey allegedly killed security guard Salim Richards, the chief said. Richards was walking in Phoenix at the time he was killed, and the investigation suggests Richards knew Cooksey and that Richards' handgun was stolen, police said.

In nearby Avondale, a man identified as Jesus Real was shot nine days later at an apartment complex, Williams said. Evidence in that investigation suggests Real's sister had a relationship with Cooksey, police said

On the evening of December 13, LaTorrie Beckford, 29, was fatally shot at an apartment complex in Glendale, police said. Evidence indicated Beckford had contact with Cooksey that day, they said.

Two days later, Cooksey allegedly killed 21-year-old Kristopher Cameron in Glendale, and evidence suggests Cameron met Cooksey to conduct a drug transaction, police said.

Less than two hours after Cameron's killing, Cooksey is suspected of kidnapping Maria Villanueva, whose sexually abused body was found in an alley in Phoenix on December 16.

"She, too, was shot to death and evidence from that scene points to Cooksey," Williams said.

Online records show that in 2001, when Cooksey was 18, he was imprisoned in Maricopa County on armed robbery and manslaughter convictions.

He served 16 years, according to police, during which time records show he accumulated 22 disciplinary infractions, including drug possession/manufacturing, fighting, disorderly conduct and assault on staff.

He was released on July 28, about four months before the killing spree began, according to the Arizona Department of Corrections.

Aspiring rapper

Daniel, the producer, last spoke to Cooksey shortly after his release. Daniel, 37, owns Cosmic Soup Recording in Phoenix and helped Cooksey record rap songs under the moniker King Playbola.

The producer was watching Netflix on Thursday when he received notifications saying people were watching and commenting on a music video he had posted for Cooksey. Cooksey wasn't good with computers, Daniel said.

When Daniel accessed YouTube and saw the comments mentioning Cooksey was accused of several murders, he couldn't believe it.

"I was amazed. I was shocked. I even thought, 'Maybe this isn't the same guy.' It is, of course," he said. "It's just crazy to me."

The two first met in 2016 when Cooksey reached out to Daniel about recording some music.

"He just found me online as a recording studio. I fit his budget. He was on a limited budget," Daniel said.

Cooksey would at times take the bus over to Daniel's home studio. Other times, Cooksey's girlfriend would drop him off, occasionally bringing her kids inside to say hello and show the children the recording equipment, Daniel said. He didn't recall the girlfriend's name.

As King Playbola, Cooksey would at times rhyme about violence and selling drugs, but Daniel thought little of it. He's recorded other rappers with similar lyrical content and chalked it up to the genre, he said. Cooksey once mentioned he had dealt drugs in a past life, Daniel recalled, but Cooksey characterized it as a mistake and said he was trying to pursue a positive path in life.

"He struck me as serious about music," Daniel said. "I never felt my life was in danger."

Usually, Cooksey would record for an hour or two, and Daniel would give him a ride home. Cooksey never said much, Daniel said, and would sometimes listen to music on his headphones for the entire drive home.

Daniel estimates he recorded two mixtapes, about 20 tracks, for Cooksey. Daniel made some CDs for Cooksey, he said, for which Cooksey never paid him.

In August, Cooksey reached out to Daniel on social media and said "he wanted to get back to work; he had more material." Cooksey told Daniel that he'd just gotten out of prison and when Daniel pressed about why, Cooksey told him he'd been arrested for DUI, a parole violation.

Their schedules never lined up, and the two didn't connect, Daniel said. That was the last he heard from him.

Though Cooksey was always nice to the producer, Daniel said he was struck by his size -- 5-foot-9 and 220 pounds, according to jail records.

"He was a big guy. If this guy was upset, he could do some harm," he said. "Like a bear -- friendly, cuddly, but you knew that if this bear wanted to, he could kill me with his bare hands."