He was given a 30-year prison sentence in 2010 for molesting five children under the age of five. But he was released in 2014 after his sentence was reduced.
The parents attacked him on October 30 in Moron, Buenos Aires, but he died on Friday.
Pecollo, 42, tried to get away but the group caught up with him and beat him, including one parent who hit the man with his own trumpet, according to witnesses.
‘When I arrived, those people were leaving,’ priest Jorge Oesterheld told local media.
‘He was in a very, very bad way, until the police and ambulance arrived. He was in a coma and died on Friday.’
The priest criticised the attackers.
‘They say they took justice into their own hands, but it was revenge, it was murder.’
Pecollo was arrested in 2007 after a mother complained that her four-year-old child had been abused. Six other cases later came to light.