BRUSSELS, Belgium (AFP) - A 24-year-old child killer disguised as Batman villain "The Joker" was found guilty on Friday of the murder of four people including two infants, with a court in Belgium ruling out mental illness in its verdict.

Kim De Gelder was found to have been lucid - "not in a demonic state or mentally troubled" - by the jury in Ghent, the judge said live on Belgian television.

He was found guilty of killing two infants aged six and nine months and their 54-year-old carer in an attack on the Fable Land nursery in the town of Dendermonde in January 2009.

De Gelder entered the nursery with his hair dyed red and his face painted white with black around his eyes - like The Joker as played by late Australian actor Heath Ledger in cult 2008 Batman movie The Dark Knight. He was also found guilty of murdering an elderly woman in a separate attack a week earlier.

After four hours of deliberations following the four-week trial, "the jury answered 'yes' to 54 questions" concerning his guilt, the senior judge said, with a "no" response to the final question concerning his mental state at the time.

De Gelder's sentence will be decided later, following fresh pleas and further deliberations by the jury and the three judges.

He risks life without possibility of parole, the heaviest sentence under Belgian law.

Last year, US youth James Holmes was accused of killing 12 people and wounding 58 in a cinema screening of a sequel to the Batman installment.