Police released new details Friday about a stabbing at a Southwest Miami-Dade assisted living facility.

According to an arrest report by Miami-Dade police, Gregorio Rojas, 51, was visiting Coral Reef Nursing & Rehab Center, 9869 SW 152nd St., where his adult brother is a patient.

Shortly after 3 p.m. Thursday, witnesses told police, 48-year-old Danilo Jose Mejia Salazar, a janitor at the center, walked past Rojas.

Rojas then pulled out a knife and attacked Salazar from behind, stabbing him repeatedly in the neck, police said.

The janitor did nothing to provoke Thursday’s attack, witnesses said. Salazar was airlifted to Kendall Regional Medical Center, where he later died.

After the attack, Rojas was seen walking “casually” to the patio of the assisted living facility. When police caught him, he was still carrying the knife.

Employees told police that Rojas appeared to be stalking Salazar before the attack. During police questioning, Rojas admitted he had an argument with Salazar at the facility a few months ago and has held a grudge since.

He also said Thursday was the first time he brought a knife to the center.

Police say Rojas will be charged with first-degree murder.