David Ludwig of Lancaster faces two counts of homicide for the Nov. 13 shootings of Michael and Cathryn Borden in their home.
Authorities said Ludwig and Michael Borden got into an argument in which the father said Ludwig was no longer allowed to see Borden's 14-year-old daughter, Kara. The shootings followed and Ludwig and the girl fled, but were apprehended the next day after a high-speed chase in Indiana.
There, Ludwig confessed to detectives, CNN reported.
"It was an intentional murder. I intended to shoot them, and I did," he said.
Prosecutors say the girl told Ludwig that "she wanted to stay with him, and they drove west with the intent to 'get as far away as possible, get married and start a new life.'"
Prosecutors have dropped kidnapping charges against Ludwig.