Mark Mawson appeared Friday in Basildon Crown Court, which ordered him sent to a secure hospital for the evaluation. He is to be sentenced in August, the Daily Mail reported.
Mawson was ordered into indefinite psychiatric detention after beating an elderly woman in London and drinking her blood. The episode left him with the nickname "The Vampire."
In February, Mawson escaped from the medium-security Chadwick Lodge Hospital in Milton Keynes after being escorted to a swimming pool on the grounds. He traveled by taxi to the home of Jackie Patterson in Chadwell-St. Mary in Essex.
During a long standoff, Mawson claimed to have a gun, although the weapon he brandished later turned out to be two pens taped together.
At another hospital, Mawson reportedly had a romantic relationship with Beverly Allitt, the country's most notorious female serial killer. Allitt, as a hospital nurse, attacked 13 infants, killing four of them.