An accountant who certified fake financial records hiding Bernard Madoff’s massive Ponzi scheme was sentenced Thursday to one year of home detention, a light punishment he received by becoming a key cooperator.

David Friehling had agreed to cooperate almost immediately after the financial fraud, one of the largest in U.S. history, was exposed in 2008. Last year, he testified for several days against five of the firm’s insiders before a jury found them guilty of participating in the scheme.