Jurors have convicted a former Iowa public official of second-degree murder for shooting his girlfriend while she was riding a lawn mower behind their home.

The jury returned its verdict Friday in the case of Thomas Lee Hansen after a weeklong trial.

Hansen acknowledged that he shot and killed 54-year-old Sharon Gerot on May 1, 2011, outside their home in Riverside. But he claimed that he only intended to scare Gerot and get her to leave after she physically and verbally abused him for hours. His lawyer says it was "an unlucky shot."

Prosecutors claimed Hansen's actions amounted to first-degree murder because he acted deliberately and out of anger toward Gerot.

Hansen retired as Johnson County's emergency management director in 2007.