Angeline Terek, 23, of Bristol and Joshua Lemonick, 20, of Newtown were arrested on Wednesday morning in connection with the crime.
Police say they were able to identify Lemonick thanks to a surveillance photo released to the media on Tuesday.
Terek, Lemonick's girlfriend, has ties to the Dover area and knew the victim, police said.
The medical examiner ruled the victim, 59-year-old Michael Gklotsos, died by strangulation.
Lemonick was arrested at his home on Cambridge Lane in Newtown at 7:30 a.m. Terek was arrested walking in the 200 block of South Olds Boulevard at 11:00 a.m.
Both suspects are being held in Pennsylvania pending an extradition hearing.
Police believe robbery was the motive for the crime.
The investigation began around 10:45 p.m. Monday when officers responded to a female caller who said she had been abducted from a residence in the 100 block of Acorn Lane in Dover.
She also told police that a man at the home was assaulted during the incident, which she described as a home invasion.
Police went to the Acorn Lane address and found Gklotsos dead inside.