Aquinas Kasbar, 19, reached a plea deal on Monday with federal prosecutors over his involvement in a July 2018 break-in at the Santa Ana Zoo.
The teenager “knew that it was a lemur and wanted to keep it as a pet,” according to the plea agreement.
He reportedly cut holes into the lemur’s enclosure, as well as enclosures housing capuchin monkeys. The 32-year-old ring-tailed lemur named Isaac was later found unharmed in a plastic container outside a hotel.
Mr Kasbar faces a maximum one year sentence in federal prison and a fine of up to $100,000 (£78,700).
The lemur was returned the next day. Other animals that were released throughout the break-in were also shortly recovered and remained unharmed.
Mr Kasbar left a note outside of the front door at the Newport Beach Marriott Bayview the day after the break-in that was labelled “SA Zoo.”
The note was placed above a crate with the animal and read: “This belongs to the Santa Ana Zoo. It was taken last night. Please bring it to police.” Another note also read: “Lemur (with tracker).”
Mr Kasbar is reportedly facing an additional 29 felony counts and 32 total charges related to a series of burglaries in the California area, the Los Angeles Times reported.
Zoo officials have said the lemur is adapting normally and was unharmed, despite being placed in an unventilated box overnight. Lemurs are among some of the most endangered group of vertebrates on Earth.