The Rev. Alfonso López Benito, 77, canon emeritus of Valencia Cathedral in Spain, was found dead in his home on 24 January.
The homicide squad is investigating because the body showed signs of suffocation.
The canon was found by the building's porter. He had entered the apartment with a friend of the priest who was worried because López had not answered his calls for days. They found the priest lying on his bed.
The deceased, or someone using his mobile phone, had sent a message saying he was going away for a week.
López Benito was ordained in 1969 and had a doctorate in canon law from the Pontifical Lateran University in Rome.
He has been a parish priest in several towns and a lecturer at the Institute of Legal Studies in Valencia and at the Faculty of Canon Law.
He has worked in the Ecclesiastical Tribunal of Valencia and is the author of several books.
In 2015, Cardinal Cañizares appointed him Canon of Valencia Cathedral.
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