Police said the suspect knew both victims, one as a roommate and one as a coworker.
ISLAND PARK, N.Y. — A 22-year-old Valley Stream man was charged Saturday with murder after two women were found fatally stabbed hours apart at a Long Island home and a Wendy’s restaurant, Nassau County police said.
Rony Yahir Alvarenga Rivera faces one count of first-degree murder and two counts of second-degree murder in the deaths of a 32-year-old woman in Valley Stream and a 42-year-old woman in Island Park. Police said both women died from multiple stab wounds to the neck and torso.
Investigators said the first killing happened around 9 p.m. Thursday inside a home on West Mineola Avenue in Valley Stream, where Alvarenga Rivera and the 32-year-old victim rented separate bedrooms. Police said the second killing happened after midnight Friday at a Wendy’s on Austin Boulevard in Island Park, where Alvarenga Rivera and the 42-year-old victim worked together. Detective Lt. George Darienzo, commanding officer of the Nassau County police homicide squad, said the suspect’s state of mind could be summed up in one word: “angry.”
Officers were first called to the Wendy’s shortly after midnight for a report of a person with a knife. They found the 42-year-old woman with stab wounds outside or near the restaurant, and medics pronounced her dead at the scene. Police said she was a mother of two. While officers were still working that crime scene, police received information about a man seeking help near a 7-Eleven in Lynbrook. Darienzo said the man told responding officers he had killed someone that night. Officers arrested him after a brief exchange.
Police then linked Alvarenga Rivera to the Valley Stream address and found the 32-year-old woman dead during a welfare check. Authorities said the two shared common areas in the home, including a kitchen, living room and bathroom, but investigators had not confirmed a domestic relationship between them. The names of the victims were not released in the earliest police accounts while relatives were being notified. Police said the motive remained under investigation, and no gang connection had been reported.
The case drew a large police response across three Nassau County communities: Valley Stream, Island Park and Lynbrook. Investigators reviewed video and photo evidence from the Wendy’s scene as they worked to connect the two killings. Officials said Alvarenga Rivera came to the United States from El Salvador as a child. Nassau County Executive Bruce Blakeman criticized federal immigration policies while discussing the case, but police focused Saturday’s briefing on the homicide investigation and the charges filed.
Alvarenga Rivera was scheduled for arraignment Saturday at First District Court in Hempstead. Prosecutors were expected to present the murder charges as detectives continued gathering evidence from both scenes. Police had not announced whether an attorney had spoken for him. Investigators said additional reports, surveillance evidence and witness interviews would shape the next steps in the case.
Outside the Island Park Wendy’s, residents and passersby described a somber scene a day after the killing. Some slowed their cars near the restaurant, and others stopped briefly to look toward the building. One woman who drove by said she wanted to acknowledge the victim, adding that a person did not have to know someone to feel grief over what happened.
The investigation remained active Saturday night, with police still withholding some details about the victims and the suspected motive. The next milestone in the case is Alvarenga Rivera’s first court appearance in Hempstead.
Author note: Last updated May 2, 2026.