
(CNN) -- Three family members of a police officer implicated in the fatal attack on a Monterrey, Mexico, casino that left 52 people dead were killed by unknown assailants in "a revenge attack" by a local cartel, the spokesman for security in the state of Nuevo Leon told reporters Thursday.
The father, stepmother and stepbrother of Officer Miguel Angel Barraza --one of the suspects held in connection with the August 25 attack -- were found dead in an apparent revenge attack by Los Zetas, spokesman Jorge Domene Zambrano said
"The message [left at the scene] refers to a kind of revenge attack," he told reporters.
The victims were identified as Miguel Angel Barraza Sandoval, 54, Maria Dolores Reyna Riva, 52, and Orlando Missael Barraza Reyna, 24.
Zambrano said authorities are considering giving protection to the families of the five other suspects.
The retaliation attack could be in connection to information Angel Barraza gave to authorities that led to the arrest of 20 alleged members of organized crime, Zambrano said.