The suspect in the deadly arson attack on a Kyoto Animation Co. studio, who suffered life-threatening burns across 90 percent of his body, has become the first person with such extensive critical burns to undergo surgery without using donor skin, medical sources said Tuesday.

Following the July fire, which killed 36 people and injured 33, Shinji Aoba was left in critical condition with burns that had destroyed the innermost skin layer, the subcutaneous tissue, the sources said.

Donor skin is typically used in initial treatment for such widespread burns because only a limited part of the patient's own skin is left available for transplanting.