Los Angeles, California (CNN) -- The Los Angeles County Sheriff's Department says the man police suspect as the "Grim Sleeper" serial killer was attacked in jail.
Steve Whitmore, the sheriff's department spokesman, said the assault happened Friday.
Lonnie D. Franklin Jr., 57, is accused of killing 10 people dating back to 1985. The serial killer was nicknamed the "Grim Sleeper" because of a 12-year period where he dropped off the radar after a series of killings and then began to kill again.
Inmate Antonio Rodriguez and Franklin were in an attorney waiting room when the assault happened, Whitmore said.
Rodriguez was not in handcuffs at the time and apparently recognized Franklin. Without being provoked, Rodriguez hit Franklin in the head twice, and he suffered minor injuries, Whitmore said.
Los Angeles police arrested Franklin on July 8 by comparing DNA found at some of the crime scenes with the DNA of the suspect's son, who was in a California lockup.
CNN's Lynn Lamanivong contributed to this article