Kim De Gelder, 20, earlier admitted to killing two babies and a 54-year-old employee of the Fabeltjesland (Fairyland) Daycare Center in Dendermonde on January 23. Twelve other people, 10 of them children, were also injured in the attack.
De Gelder has also confessed to stabbing to death 73-year-old Elza Van Raemdonck de Vrasene in the neighboring village of Beveren on January 16. According to local media reports, his DNA was found in her home.
Earlier De Gelder had denied killing the Belgian pensioner.
According to investigators, De Gelder fled the scene on a bicycle, as he did from the daycare center a week later. Nothing was reported missing from de Vrasene's home.
"There is proof that he has psychological problems, but that will have to be supported by a psychological report," the killer's attorney, Jaak Haentjens, said earlier.
The first reconstruction of the crime scene has already been conducted without the suspect's participation.
Prosecutors earlier stated that De Gelder was not under the influence of drugs or alcohol during the attack on the daycare center and that he had no earlier criminal or psychiatric background.
However, De Gelder's lawyer said earlier that "At 15-16 [years old], he was extremely depressed and his parents even wanted to place him in a psychiatric ward, but that didn't happen because he was going through therapy and the psychiatrist believed that it wasn't necessary. Kim was hearing voices in his head at that time."
