OAKLAND -- A Pittsburg mother and son have pleaded guilty to conspiring to file false tax returns, a prosecutor said Monday.

Tonya Gilard, 44, and Tierre Crummie, 24, appeared in federal court in Oakland and accepted plea deals last week, according to a statement from Melinda Haag, U.S. Attorney for the Northern District of California.

Haag said the pair had filed false federal income tax returns with the IRS in 2009. Gilard used the personal identifying information of others, including her son, to file the false returns. The duo also filed tax returns in their own names that falsely claimed the first-time homebuyer's credit, Haag said.

In total, prosecutors said, the mother and son filed 91 false federal income tax returns and netted $688,687 in refunds from the IRS.

Conspiracy to file false claims carries a maximum 10 years in prison and a $250,000 fine; Gilard and Crummie are schedule to be sentenced Sept. 5.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.