Upper Darby police Superintendent Michael Chitwood says 26-year-old Samuel Nyenka was arrested last week.
Chitwood says the alleged victim did not immediately come forward because Nyenka is her sister's boyfriend. It was only after she learned she was pregnant that she spoke with police four months later.
Chitwood said Tuesday that Nyenka denied any sexual contact with the woman, so with the alleged victim's permission they obtained a DNA sample from the fetus. He says tests determined Nyenka was the father.
Nyenka is facing charges including rape and sexual assault. He is being held on $150,000 bail at the Delaware County prison. It was not clear if he had an attorney.
