The Justice Department is investigating Pennsylvania’s new voter identification law, a letter sent to the state government Monday indicates. The letter from Assistant Attorney General Tom Perez seeks a variety of records related to the implementation of the voter ID, which was passed in March and is set to take effect before the November election. Among the items Perez is requesting are databases of Pennsylvania voters and holders of drivers’ licenses and similar state IDs. It’s not clear precisely what triggered the letter but it refers to an estimate Secretary of State Carol Aichele issued earlier this month indicating that 9.2 percent of the state’s 8.2 million voters don’t have a state-issued photo ID. However, a state-issued ID is not the only form of acceptable voting ID, which includes passports, military ID and some student IDs.