Forty-five-year-old Mark Allen Shirey answered "Yes" when asked in Bedford County Court on Friday whether he killed 49-year-old Michael Simpson of Cumberland Valley in March 2011.
Defense attorney Steven Passarello said the first-degree murder plea would spare his client execution in what "was always a death-penalty case."
Relatives said Shirey and his ex-wife had four children but divorced about a decade ago. Authorities said he broke into Simpson's home and killed him when he arrived home.
Shirey was arrested three days later at a Maryland campground. Officers said he told them "A guy takes your family away from you. What's a guy supposed to do?"