A St. Paul man is charged with murder for his alleged role in a shooting that was the culmination of an escalating feud with his girlfriend's estranged husband.

The Ramsey County Attorney's Office charged James Edward Hagen, 32, with second-degree murder Wednesday. Prosecutors believe Hagen shot and killed Jonathan Diaz, 35, of St. Paul, who was found in lying in a yard in the 800 block of York Avenue with multiple gunshot wounds Monday evening. Hagen's next court hearing is Friday.

According to charging documents, fights between Hagen and Diaz escalated months before the shooting.

Officers first responded in August to the same address in the 800 block of York Avenue for reports of a shooting. They found Hagen with bullet wounds to both legs, but he denied knowing who the shooter was or why they fired at him. But Hagen's girlfriend, referred to as "CD," said Diaz shot Hagen out of jealousy.

CD later explained she is married to Diaz, although they separated four years ago. She has dated Hagen for the past three years, and said that he and Diaz "don't get along."

Diaz was arrested the day after that shooting. He wasn't charged because Hagen did not cooperate and prosecutors could not prove a case against Diaz without a reasonable doubt.

On Monday responding officers found CD performing CPR on Diaz, who was lying unconscious near a garage door in a pool of blood. He had no pulse and had stopped breathing. Officers helped Diaz until medics arrived, but they pronounced him dead at the scene.

Witnesses said Hagen shot Diaz and fled on a bicycle before ditching it to run on foot. Witnesses also said a white Cadillac circled the area after the shooting.

Investigators canvassed the scene and found nine bullet casings — seven inside the garage and two outside. A 9-millimeter handgun with an empty magazine was also found in the garage, and examination suggested it fired the bullet casings recovered from the scene.

A woman referred to as "KA" said she was friends with Diaz, and claimed to be with him moments before the shooting. KA said she and Diaz drove past the York Avenue home earlier that day, and Diaz greeted his son who was outside the home. Diaz picked up KA in a white Cadillac later, returning to the York Avenue home where he asked KA to drop him off. She said gunshots rang as she drove away.

"KA tried to call [Diaz] to see if he's okay, and she eventually left the area in the white Cadillac," the charging documents read. "After the shooting, KA saw a white male with facial hair running in the neighborhood and looking behind him as if someone was chasing him."

CD's teenage daughter said she saw the incident, but did not want to get her mother in trouble because she believed the mother was not honest about the shooting. When interviewed at police headquarters, away from her mother, CD's daughter said Diaz shot Hagen at the same home before — and that Hagen threatened to kill Diaz the next time he saw him.

The daughter claimed to be in the kitchen with CD when they heard 10 loud bangs. Running outside, she said Hagen stood in the garage doorway near Diaz. Diaz was on the ground and shaking. The daughter thought Hagen shot Diaz, and said CD ran towards Diaz as Hagen yelled "I told you I was going to kill him!" She said Hagen fled on a bike afterwards, but was unsure if he took a gun with him. She believed Diaz was unarmed.

Police also interviewed CD's teenage son, who heard the pops as he cleaned the bathroom. He heard his mother screaming outside, and said he ran outside to see Hagen panic and leave on a bike.

When interviewed by police, CD said Hagen and Diaz don't get along. She said Diaz drives past her York Avenue home to see his son, but Hagen found out and began arguing with her. She said Hagen left after they argued, and she heard bangs outside sometime later. CD said she went outside and found Diaz dying on the ground, but denied seeing Hagen there.

Police arrested Hagen during a Tuesday traffic stop. An autopsy by the Ramsey County Medical Examiner found Diaz died from six gunshot wounds to his body. He marked the 14th St. Paul homicide this year. According to a Star Tribune database, there were 18 by this time last year.