The death toll in last week's arson attack on a Kyoto Animation Co. studio rose to 35 as a man being treated at a hospital died Saturday, police said.

Some of the people injured in the incident remain hospitalized. The police have not released the identities of the victims.

The police have yet to question the suspect, Shinji Aoba, who has severe burns and remains in serious condition. He is suspected of entering Kyoto Animation's three-story building on July 18 and igniting gasoline.

Investigators searched Aoba's home in Saitama, near Tokyo, on Friday for clues that might point to a motive. Investigative sources said confiscated evidence included products of Kyoto Animation.

According to different investigative sources, the animation studio received repeated email threats from the same internet address between last September and November. Some of them were addressed to specific employees, they said.

The sender of the email used anonymous communication software called Tor which makes tracing of senders difficult, they said.