According to court documents, police believe Sean Burton attached a GPS tracking device to James Stropas' sport utility vehicle sometime before stabbing him last week.
Burton, of Newark, Del., was arrested June 21 in Springfield after being pulled over behind the wheel of Stropas' SUV. Stropas' dead body was on the passenger side floor. Burton told police Stropas came at him with a knife and he defended himself.
Burton is being held without bail on charges including first-degree murder.
Police say Stropas had been dating Burton's estranged wife.
