Sammamish resident David Costa, 77, recently pleaded guilty and is awaiting sentencing as one of Washington’s biggest Social Security frauds.

Costa fraudulently collected $297,948 of his mother’s Social Security benefits following her death in 1989. While he originally thought the payments were coming to a joint bank account from an annuity, in 1992 he learned they were Social Security payments.

Rather than alert authorities and pay back the $40,000 that had wrongly been paid, Costa continued to collect the benefits for more than 15 years. He forged his mother’s name on documents and substituted his address for hers on all records, updating it three different times over the years. Costa pleaded guilty on June 3.