Officers found the woman's “badly decomposed” body at a Madrid flat on Wednesday after receiving a call from neighbours who reported a “strong odour”, a police spokesman said.
Police then detained the woman's 62-year-old son for fraud for failing to report her death aged 92 and continuing to collect her pension, he added.
“The son did not do what he should have done,” the spokesman said, adding that the man lived in the flat with his mother's remains for “several months, possibly almost a year”.
The grim discovery was made on Wednesday in the flat at number 12, Calle Salvador Alonso in the San Isidro neighbourhood of Madrid.
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