Having your FTC or police reports on hand can help with these next steps from IdentityTheft.gov:

Close fraudulent accounts. Call companies where thieves have opened accounts in your name and ask them to close the accounts. Request a letter confirming that: 1) the account isn't yours, 2) that you're not responsible for it, and, 3) that the company will remove it from your credit report.
Dispute fraudulent charges. Call companies where the bogus charges were made and ask them to remove the transactions. Then, request a letter saying they removed the bad charges.
Correct credit reports. Write each credit bureau and ask them to "block" fraudulent accounts and transactions from your credit report. If you include your FTC report, the credit bureaus are required to comply. What's more, once bad accounts are "blocked," companies can no longer try to collect that debt.

Even after you take all of these important steps, you'll want to keep an eye on your accounts for some time — and be ready to take quick action if there's any sign of further fraud. You should treat your personal information as if it's the most precious thing you own.