IOWA CITY, Iowa (AP) A 44-year-old radiologist followed his ex-girlfriend to her new boyfriend's home in a small Iowa town before killing her and committing suicide in a burst of violence that left residents shaken, a prosecutor said Friday.

Timothy Roses gunned down Lindsay Nichols, a 22-year-old former high school cheerleader, in the street Wednesday night shortly after her new boyfriend called 911 from inside his home, Buchanan County Attorney Shawn Harden told The Associated Press Friday. Roses then shot himself in the chest, Harden said.

Revealing the most detailed account yet of events leading to the murder-suicide in Jesup, Harden said Nichols and Roses met at Covenant Medical Center in Waterloo where she was studying radiography and he worked on staff when he wasn't practicing in Texas. They had a months-long relationship that Nichols ended in February, he said.

Nichols then started a relationship with Jesup resident Chase Weber, and posted that news on her Facebook page Wednesday. Roses was upset by the breakup and had been sending Nichols many text messages and the change in her relationship status on Facebook may have "escalated matters," Harden said.

In a rental truck with out-of-state license plates, Roses followed Nichols the 15 miles from Waterloo to Jesup, a town of about 2,500 residents. When she got out of her vehicle outside Weber's home, Roses pulled in behind her, got out and they began to argue, Harden said. Roses ordered Nichols to get into her vehicle and pulled a gun when she refused. On hearing the commotion and seeing the gun, Weber called 911.

"As he's on the phone with dispatch relaying what's going on, one shot is fired. That hits Lindsey," Harden said. "At that point, (Weber) runs from window to door. On his route between window and door, he hears another gunshot. When he gets to the door, both individuals are on the ground."

Investigators have processed the physical evidence from the scene, and are interviewing friends and family members to piece together a timeline of events that led to the murder-suicide, Harden said.

Nichols had complained on Facebook that she felt like she was being watched, but she never filed a complaint with law enforcement, Harden said. Investigators recovered three cellphones from the scene and planned to check the text messages, he said.

Harden said it was not clear whether Roses routinely used a rental vehicle when he was in Iowa, or if he had rented the truck specifically to follow Nichols without detection. He said Roses apparently had a family back in Texas.

Roses had an office in Plano, Texas, and lived in nearby Rockwall with his wife, according to the Plano Courier-Star newspaper, which cited district appraisal records. Roses graduated from the University of Arkansas medical school in 1993 after doing a residency at the University of Missouri, license records show.

Harden, the top county prosecutor since January 2011, said the murder-suicide was the worst violence he's seen and that the case hit home for more than one reason: he lives about a block from the murder scene and his wife is a deputy sheriff who works with Nichols' father, who is also a deputy for the county.

The Iowa Division of Criminal Investigation is conducting the investigation with assistance from local authorities.

Hundreds of residents gathered at Waterloo East High School on Thursday night to mourn the death of Nichols, who graduated from there in 2008. She played sports, was a cheerleader and was on the honor roll, friends said. She was from nearby Evansdale, where her late grandfather had served as mayor.

Nichols graduated from the two-year radiography program at Covenant last June, a hospital spokeswoman said. Roses was on the hospital's staff for the last several years but also worked at a private practice radiology group.