A man has been arrested for the murder of a woman at a Glendale, Arizona, bus stop last month, where police said he used a metal pen to stab her in the neck.

James Marshaun Christopher Weekly, 27, confessed to the murder, according to Glendale Police Officer Moroni Mendez, who spoke during a Friday news conference, though Mendez suggested Weekly’s version of events was that he acted in self-defense.

Weekly has been charged with second-degree murder.

Love true crime? Sign up for our newsletter, The Law&Crime Docket, to get the latest real-life crime stories delivered right to your inbox.

On April 28, just after 9 p.m. local time, officers responded to reports of a stabbing near the corner of 83rd Avenue and Cardinals Way. It was there that they found an injured Judy Ann Lopez, 62. She was brought to a hospital, where she died from her injuries.

“It was a horrible thing that happened to my sister. No family should have to go through that, but a lot of families do,” Linda Lopez, Judy’s sister, said at the press conference before profusely thanking detectives for their work on the case. “Justice will be served for my sister.”

Mendez described the difficulties in finding a lead in the case due to there being no video surveillance of the stabbing. But footage from a Valley Metro bus helped carry the investigation forward.

“We had discovered that Judy had boarded one of our Valley Metro buses in the valley and got off at that intersection,” he said, adding: “It was seen on bus video that Judy had a cell phone with her. She had a cell phone with her when she was getting off the bus, and after she was transported to the hospital and the scene was completely gone through, the cell phone was nowhere to be found.”

“So it was after extensive detective work and investigating that we were able to obtain cell phone data records, and those are the ones we used to locate where that cell phone went,” Mendez continued.

Detectives learned the phone had been brought westward into a nearby neighborhood, and by checking home surveillance cameras, they learned a man, later alleged to be Weekly, had moved through the streets shortly after the stabbing.

Police secured a search warrant for Weekly’s residence and executed it on Thursday.

“James was apprehended, and a cell phone matching Judy’s cell phone was located inside the home – not to mention the same exact clothing that he was seen wearing in the bus, the same bus that Judy was in and in security camera videos, was also discovered,” Mendez recounted.

According to the police officer, Weekly “confessed to quite a few things” including that “he did it – he said that he stabbed her” and used a metal pen to “poke her in the neck.”

“And it’s unfortunate, but it’s difficult to understand what the motive was,” Mendez continued, adding that Weekly maintained Lopez was “suffering some sort of medical episode” and he “tried to see if she was okay, [and] she swatted away his hand,” cutting it, and that’s when the assault happened.

Weekly expressed remorse for what he did, telling authorities he wanted Lopez’s family “to know this was caused by a misunderstanding,” according to court documents reviewed by AZFamily.

He reportedly added that he was “not trying to kill her,” claiming he “wished he would have handled the situation differently.” Still, police said Weekly told them several times in his interview that he “wanted her to feel pain and bleed because he was bleeding.”

The suspect is accused of being affiliated with the Gangster Disciples gang originating in Chicago.