Devon Saunders, who is 46, was convicted Thursday of first-degree murder in the death of Shernell Pierre.
The 26-year-old nurse had just left work at the Misericordia hospital in 2008 when she was killed.
Crown prosecutor Neil Wiberg presented a case based on circumstantial evidence that Saunders killed Pierre in a jealous rage.
Jolin Thompson says her sister and Saunders had a strained relationship because he was married.
Saunders is facing life in prison with no chance of parole for 25 years.