He was wanted for the murder 25-year-old Armando Vidana of Pomona, a known gang member was shot to death on Sept. 29.
After talking to an informant following Caballero's arrest, investigators say the suspect may also be involved in the deaths of a man and woman in two separate locations over the weekend.
Officials say 29-year-old David Padilla of El Monte was found Saturday on some railroad tracks under a freeway overpass in the 3700 block of Walnut Avenue in Chino. It appeared the father of four died of some sort of trauma to the upper body.
Family members say Padilla had simply vanished on Thursday night.
"It's still an ongoing investigation. They're not telling me anything either. So all I know now is that my husband's body was found here and he's not coming home," said Victoria Padilla, the victim's wife.
Later that day, investigators found the body of a 32-year-old Covina woman. The body of Lorraine Minjarez was found in what appeared to be a shallow grave in the Angeles National Forest along Mt. Baldy Road.
Detectives won't say how either victim was killed, but they do believe the murders are connected. Investigators from several agencies are working together on the case.
"At this point in the investigation, we're working with detectives from the Chino Police Department, along with detectives from the Pomona Police Department, and we're trying to determine exactly what happened along with the circumstances surrounding these two murders," said Lt. Dan Rosenberg, the Los Angeles County Sheriff's Department.
Caballero is being held without bail.
If you have any information about the murders, you're asked to call the Los Angeles County Sheriff's Department at (323) 890-5500.
Eyewitness News reporters Amy Powell and Leo Stallworth contributed to this report.