Police have been looking for Justin Slater since Thursday when his brother Gregory was found dead in his home.
Saturday afternoon, a clerk at a 7-11 in Wardensville, West Virginia recognized Justin as a fugitive, and he was arrested.
About 30 miles away, in a home that once belonged to Justin's parents in Lost River, West Virginia, police found a body that they believe belongs to Justin's ex-girlfriend, Kayleigh Plamondon.
An official identification will not be made until an autopsy report is completed.
Police say Slater was driving a black SUV stolen in Pennsylvania.
He is being held in Hardy County.