The National Flood Insurance Program began mailing letters to superstorm Sandy victims Monday to start the process of reviewing thousands of claims that may have been underpaid after the 2012 disaster.The first round of roughly 15,000 notices are going to homeowners whose properties were inspected by engineers, some of whom are suspected of falsifying damage reports. Letters to the remaining 129,000 storm victims who filed claims are scheduled to go out in waves through mid-June.The effort to reopen up to 144,000 Sandy claims comes after dozens of homeowners accused private companies hired by the government-run insurance program of forging documents to improperly deny settlements.The allegations have led to a criminal probe and the departure of two top officials at the flood insurance program.The letters will direct homeowners who want their claims reopened to contact the Federal Emergency Management Agency, which runs the flood insurance program, within 90 days by registering online or calling the toll-free number 866-337-4262.After a brief interview, FEMA will give homeowners two weeks to submit documents proving they were underpaid.If homeowners don’t have receipts, the agency will accept sworn statements for expenses up to $7,500 per claim. FEMA will also extend the two-week deadline if storm victims need more time to compile evidence.Homeowners who disagree with the outcome will have the option to appeal to a third-party arbiter. The head of the flood insurance program, Brad Kieserman, will have the final say over any settlements.Homeowners who have their claims reviewed won’t automatically receive a bigger settlement. Some may wind up having to repay the flood insurance program if adjusters determine their initial settlement was too large. Kieserman, however, has said he expected those instances to be rare.