The Justice Department is accusing the Republican congressman who is leading an investigation into “Operation Fast and Furious” of “mischaracterizing evidence” and “maligning” federal law enforcement officials by questioning Sunday whether the FBI was trying to cover up the existence of a third gun at the scene of Border Patrol agent Brian Terry’s murder last year.

“The FBI has made clear that reports of a third gun recovered from the perpetrators at the scene of Agent Terry’s murder are false,” the department said in a statement Monday…

In its statement late Monday, the Justice Department offered its first public explanation of “K1.”
“According to the FBI, the item that Chairman Issa refers to as ‘K1’ is a blood sample from Agent Terry, not a firearm,” the statement said. “For this reason, it was not listed on the ballistics report prepared by the FBI.”

The Justice Department said law enforcement officials refer to some items seized at scenes as “known” items — or “Ks” for shorthand.

“Unfortunately, this most recent false accusation not only maligns the dedicated agents investigating the murder of Agent Terry, it mischaracterizes evidence in an ongoing case,” the Justice Department said in its statement Monday night.

Rep. Elijah Cummings of Maryland, the ranking Democrat on Issa’s committee, also criticized Issa for fueling what he called “baseless speculation” about tampered evidence…