Ruben Sanchez, 84, was found severely beaten at his apartment on the 1800 block West Glenoaks Boulevard around 5:30 a.m. Monday.
Authorities say the victim's grandson, who lives in the unit above, found the man covered in blood. Sanchez was rushed to the hospital where he later died.
Investigators initially thought they were dealing with a possible burglary that went wrong. According to police, there was no forced entry, and the residence was ransacked.
After further investigation, detectives identified the suspect as 22-year-old James Adrian Sanchez, a family member who did not live at the apartment complex. The suspect was located in El Cajon in San Diego County and arrested early Tuesday morning by Glendale police with the assistance of the U.S. Marshal's Task Force.
Detectives have not released a motive for the crime. The suspect was booked into the Glendale City Jail for murder. No bail has been set. His arraignment is scheduled for Thursday.
Sanchez's death marks Glendale's first homicide this year.
The investigation is ongoing. Anyone with information was asked to contact homicide detectives at (818) 548-3987.