Stoss, of Pittston Township, was convicted in March 2012 of first-degree murder in the brutal beating of Calabro, 48. Prosecutors say he then dumped her body into the Susquehanna River near the Riverfront Park in Pittston.
Her body was found 10 days later, washed ashore in Kirby Park in Wilkes-Barre.
Prosecutors say Stoss was with Calabro in the last few hours of her life, hanging out at a Pittston bar, a friend's house and then going to the Riverfront Park where Stoss wanted to buy drugs.
That's where, prosecutors say, Stoss punched Calabro in the face, then choked her to the point that she became unconscious.
Stoss then took a rock and smashed Calabro's skull in, before dumping her belongings and her body into the river, prosecutors alleged at Stoss' trial.