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A Texas radiologist fatally shot his former girlfriend outside her new boyfriend's home in Jesup, Iowa, then killed himself, moments after the boyfriend called 911 to report the confrontation, authorities said.

The Buchanan County Attorney's Office identified the dead as Lindsay Nichols, 22, of Waterloo, and Timothy Roses, 44, a radiologist from Rockwall, Texas. Both died at the scene on the night of March 21, 2012, according to investigators.

Nichols and Roses met at Covenant Medical Center in Waterloo, where she was studying radiography and he was on the medical staff, according to the WCF Courier. Nichols ended the months-long relationship in February and began dating Chase Weber of Jesup. She posted the new relationship on Facebook, which authorities said angered Roses.

Roses followed Nichols about 15 miles from Waterloo to Jesup in a rental truck with out-of-state plates, prosecutors said. When she stepped out of her car at Weber's house, the two argued. County Attorney Shawn Harden said Roses ordered Nichols back into her vehicle and drew a handgun when she refused. Weber called 911 after seeing the weapon.

The county attorney's office released the recording of Weber's call on May 2. On the tape, Weber urges a dispatcher to hurry and can be heard yelling 'oh my god' as gunshots sound in the background, according to accounts of the recording. Harden said Roses shot Nichols in the chest, then shot himself.

Investigators said Roses used a 9 mm handgun that he was not licensed to carry in Iowa and had bought from a coworker in Waterloo. Harden said he hoped federal prosecutors would file charges against the person who sold it.

Nichols graduated from Waterloo East High School in 2008, where she was a cheerleader and honor student. Her family later filed a lawsuit against Roses' estate. Roses was married and had children in Texas, according to news reports.