Daniel Hernandez is being held without bail at the Los Angeles County Men's Central Jail.
Authorities responded to an apartment in the 1700 block of College View Drive to do a welfare check just after 4 a.m. Friday. When there was no response at the door, officers made entry and found a body in the bedroom. The victim, identified as 23-year-old Jacqueline Alamillo, was declared dead at the scene.
About an hour after police responded, Hernandez was found a few blocks away yelling at cars and acting irrationally, investigators said.
The motive is unknown at this time, and the cause of death has not been determined.
Anyone with information is urged to call the Los Angeles County Sheriff's Homicide Bureau at (323) 890-5500.