The Chester County district attorney said Tuesday that his office was investigating possible election fraud after receiving complaints from citizens and county Republican and Democratic leaders about an anonymous mailing sent to voters last week.

The letter, which sharply criticized District Judge Rita A. Arnold, was sent to registered Democrats and Republicans in District 15-2-06, where Arnold was seeking reelection against Don Skomsky, said District Attorney Joseph W. Carroll. Both candidates were cross-filed.

Results in the race were not definitive late Tuesday.

Although the mailing was not signed, Carroll said copies sent to Republicans had a return address listing a GOP group that did not exist while the letter that went to Democrats featured a bogus Democratic organization. The district encompasses Birmingham, Caln, East Bradford, and West Bradford Townships, and the Borough of Downingtown.

Carroll said the focus of the probe was not "the veracity of the allegations" but whether the mailing constitutes forgery or violates election law by falsely purporting to represent an organization.

"Both party leaders seemed to be offended by it," he said.

Among the letter's criticisms was that Arnold had misused her office by showing favoritism to relatives.

Neither Skomsky, president of Integrity Engineering Inc. of West Chester, nor Arnold could not be reached for comment, but a statement on Arnold's election website said: "This malicious attack is merely a smear tactic by anonymous parties to discredit Judge Arnold's stellar reputation in the community by making personal attacks against her and her family."

Joseph "Skip" Brion, who heads the county Republican Party, issued a statement supporting Arnold and condemning the mailing: "By masquerading as an anonymous, fake political action committee, Arnold's opponents show an extreme lack of judicial temperament and total disregard for the law."

County Democratic Chairwoman Michele Vaughn also denounced the mailing in a statement, saying "the return address listed was that of our Democratic Committee headquarters with the organization listed as CC Dems for Justice.. . . No organization by that name has ever operated out of this address."

At the polls Tuesday, the letter prompted outrage from voters. "I've lived in the township for 27 years and have never seen anything like this," said Birmingham resident Martin Wolf, echoing the sentiments of many. "I'm offended by the letter."

Mary Evans, a Republican committeewoman in Birmingham Township, said she hoped the letter's writer would be prosecuted.