A Philadelphia man pleaded guilty yesterday in federal court to knowingly employing more than 50 illegal immigrants to work at a string of car washes in six states, including Pennsylvania and New Jersey.

According to the U.S. Attorney's Office, Robert Kramer, 56, was the general counsel of Mace Security International and the chief operating officer of Car Care Inc., a wholly owned subsidiary of Mace that operated more than 50 car washes, including in Norristown, Flourtown, Bryn Mawr, and Cherry Hill. Officials said that from at least 2000 through March 13, 2006, the company hired undocumented workers under the names of former employees. Those workers were paid with checks in the names of the former employees. Kramer faces a maximum sentence of six months in prison and a fine of $150,000 when sentenced Sept. 15. - Inquirer staff