Emilio Alvarez is the brother of Delores Alverez. She was the nanny of the Mill family, mostly supported by Anna Mill, who welcomed her into the home and even convinced her family Delores would be a great person to have around to help keep the household maintained.
When Anna's husband Julian and her children Rachel and Charlie were stabbed to death while they slept, Delores hid in Emilio's home since she was the prime suspect, especially since the murder weapon was in her house and she became infatuated with Julian before the murders. Emilio insisted for the detectives to not search through his house and claimed racial prejudice, but Delores was found and arrested, despite Emilio pleading she's not guilty.
It was revealed Delores stumbled across the family members and tried to wake them, and she took the knife because she picked it up without thinking and feared she'd be blamed with her prints on the weapon. When Anna herself was revealed to be the killer, Delores was released. (SVU: "Caretaker")