Jurors in Delaware County reached a verdict on Friday in the case of 26-year-old Samuel Nyenka of Upper Darby.
The woman testified that she was assaulted at Nyenka's home in November 2009 after his wife had left for work.
But defense attorney Mary Beth Welch said she did not go to police until almost five months later, and Nyenka's wife testified that she was not working then.
Assistant District Attorney Joseph Lesniak said Nyenka initially denied having had sex with her. He told the Delaware County Daily Times that he is considering a retrial on the remaining charge.
Information from: Delaware County Daily Times