When the alarm was triggered, he would show staff a plastic bag containing DVDs he had bought elsewhere and they would think the alarm had sounded in error.
In all, the defendant stole about 27 DVDs, prosecutor Sergeant Ross Hutton told the court.
On February 29, after he had been trespassed from the library, Lockhart-Jones was seen in the building.
Staff noticed him taking several DVDs to the toilet area and confronted him. He admitted what he had been doing. Reparation totalling $1012.49 was requested.
Counsel Milton Sperring said the defendant was under a compulsory treatment order at Wakari Hospital.
Judge Michael Crosbie convicted Lockhart-Jones and remanded him for sentence on May 17.