The dead priest was found by parishioners after he did not show up for evening Mass at St Anthony of Padua church, Fides reported.
His body had wounds on various parts, which suggested that he attempted to struggle for his life, but he was killed by being struck with a large crucifix.
The attacker took the mobile phone and computer from the rectory.
Police reported that Father Karczewski had already been assaulted in his home a year ago.
The priest belonged to the province of St. Maximilian Kolbe in Gdansk, Poland, and had been serving in Ecuador since 1995.
