The incident happened at about 3 p.m. on Sunday, March 6, at "Centro De Alegria" Pre-School in the 400 block of North Soto Street.
The suspect ransacked the school, taking various items of property including money and keys. Surveillance video shows the man getting naked in the entryway of the preschool and walking around for several minutes, engaging in sexual behavior.
A similar incident happened at the same school last November.
Police are asking for the public's help in identifying the man. Anyone with information was asked to call Los Angeles police at 1-877-LAPD-24-7 (877-527-3247).