WASHINGTON—Emails and other documents released Wednesday suggest the Internal Revenue Service's procedures used to target conservative groups for added scrutiny were developed by lower-level employees.

Republican lawmakers seized on the emails—written in 2011 about decisions made in 2010—as evidence that they were kept in the dark about the practice far too long. The Treasury Department inspector general's office overseeing the IRS received the internal emails in July 2012, but didn't issue a report condemning the practice...