In a harrowing incident that unfolded in the early hours of June 25, 2024, Maricopa County Sheriff’s Office (MCSO) detectives arrested 60-year-old Robert McGrath in connection with the brutal murders of his wife, 53-year-old Marcia McGrath, and his mother-in-law, 77-year-old Thea Merlino. The double homicide has left the Sun City community in shock and mourning.
At approximately 3:07 a.m., MCSO dispatch received an emergency call reporting a disturbance involving a male subject with a gun near the 13000 block of Newcastle Drive in Sun City. The caller, a concerned neighbor, reported hearing a loud noise from an adjacent apartment. When the caller attempted to check on the welfare of the residents, they encountered Robert McGrath in the doorway, armed with a handgun. McGrath threatened the caller at gunpoint, ordering them to the ground and warning them not to move. The caller fled back to their own residence and immediately contacted authorities.
Deputies responded swiftly to the scene and were met with cries for help from within the apartment. Upon entry, they discovered one deceased female and another severely injured, both suffering from gunshot wounds. Deputies administered life-saving measures until fire personnel arrived and transported the injured woman, Marcia McGrath, to the hospital. Tragically, she was pronounced dead shortly after her arrival. The deceased at the scene was identified as Thea Merlino.
“Our thoughts continue to be with the victims’ family members. I would like to commend the brave actions of the community members for their observations and courage in swiftly reporting this tragic incident,” said Sheriff Russ Skinner. “I would also like to recognize our communications staff, deputies, and detectives for their immediate response, investigative follow-through, and apprehension of this dangerous suspect. As a law enforcement agency, our number one priority is keeping our community members safe and quickly responding to their public safety needs.”
Detectives located Robert McGrath at his residence in El Mirage, Arizona, and arrested him without incident. He has been booked into the intake Transfer Release facility on multiple charges, including:
- 2 counts of 1st-degree murder
- 1 count of burglary
- 2 counts of aggravated assault
- 2 counts of kidnapping
- 1 count of armed robbery
The double homicide has deeply impacted the Sun City community. Neighbors and local residents have expressed their shock and sorrow over the tragic event. The quick action of the neighbor who reported the incident, coupled with the rapid response from law enforcement, has been praised by many.
“This incident has shaken our community to its core,” said a local resident. “We are grateful for the swift actions of the MCSO deputies and detectives, and our thoughts are with the victims’ family during this incredibly difficult time.”
The incident has also sparked discussions on domestic violence and the importance of community vigilance. Advocacy groups are urging individuals to be aware of the signs of domestic abuse and to report any suspicious activities to authorities promptly.
Sheriff Skinner emphasized the MCSO’s commitment to ensuring the safety of the community and providing support to the victims’ families. “We remain dedicated to serving and protecting our community. Our detectives will continue to work diligently to ensure justice is served for Marcia McGrath and Thea Merlino,” he said.
As the investigation continues, the MCSO is urging anyone with additional information related to the case to come forward. Tips can be provided anonymously to the Maricopa County Sheriff’s Office or through their website.
This tragic incident underscores the critical role of community members and law enforcement in maintaining public safety. The Sun City community, while mourning the loss of two lives, stands united in the pursuit of justice and support for those affected by this devastating event.
