Congress's investigation into IRS political targeting accelerated Wednesday, with a referral for the criminal prosecution of a former Treasury official and new evidence to back it up. In a letter to Attorney General Eric Holder, House Ways and Means Chairman Dave Camp recommends the Justice Department proceed on three probable criminal actions taken by former director of Exempt Organizations Lois Lerner.

The letter, which was endorsed in a party-line Ways and Means vote Wednesday morning, discloses new evidence suggesting that Ms. Lerner used her position to single out conservative groups for scrutiny not applied to left-leaning groups. Investigators also charge that she misled investigators in her original conversations with the Treasury Inspector General and potentially disclosed confidential taxpayer information by using her personal email address for IRS business.

The most troubling new evidence are documents showing that Ms. Lerner actively corresponded with liberal campaign-finance groups Democracy 21 and the Campaign Legal Center, which had asked the IRS to investigate if conservative groups including Crossroads GPS were violating their tax-exempt status. After personally meeting with the two liberal outfits, Ms. Lerner contacted the director of the Exempt Organizations Examinations Unit in Dallas to ask why Crossroads had not been audited.

"You should know that we are working on a denial of the application," Ms. Lerner wrote in an email. "Please make sure all moves regarding the org are coordinated up here before we do anything." The Cincinnati agent assigned to the case at the time, Joseph Herr, noted on his timesheet, "[b]ased on conference, begin reviewing case information, tax law and draft/template advocacy denial letter, all to think about how best to compose the denial letter."

Mr. Herr had not made any indications in 2012 of an intent to deny the application, nor was any denial recommendation contained in the November 2011 analysis of the group by Exempt Organizations lawyer Hillary Goehausen. Crossroads GPS, which was cofounded by Journal contributor Karl Rove, says it applied for tax-exempt status in 2010 but still hasn't received formal IRS approval.