Tokyo, Japan (CNN) -- Police have found the mummified body of a man believed to have been Tokyo's oldest man, who may have in fact died some 30 years ago, officials at the city's Adachi Ward said.

Sogen Kato, who was born on July 22, 1899, would have been 111 years old if he were alive today.

Police are still investigating the case, but officials told CNN they found newspapers in his room dating back three decades, and think he might have been dead for at least that long.

According to a local newspaper, Kato's granddaughter told police he had locked himself in his room some 30 years ago, saying he would become a living Buddha.

Kato was previously thought to have been living with his 81-year-old daughter, her 83-year-old husband and their two children.

Local officials had visited their home repeatedly throughout the years to check on Kato's well-being, but family members had rebuffed their visits. One official grew suspicious about Kato's safety earlier this year, and reported his concerns to the ward office. Police investigated and discovered what is thought to be Kato's mummified body.

His wife, a former teacher, died six years ago at the age of 101. Kato had been receiving his late wife's pension payments.