(CBS) — U.S. Sen. Mark Kirk on Friday criticized the recent release of Taliban members for captive American soldier Bowe Bergdahl and called for an investigation.

Kirk says Guantanamo Bay should be a “black hole” for terrorists and they should never get out.

Kirk appeared in Rosemont with Ken Luccioni, the stepfather of a Private First Class Martinek. The 20-year-old Illinois native was killed in 2009 on a mission to find Bergdahl.

“I’d like to know why five of the worst that were on a list of this administration’s advisory group to not be released ended up being released,” Luccioni said.

He says the Defense Department is not being truthful.

Kirk, a North Shore Republican, is calling for a full investigation into the prisoner swap.

The senator, along with 10 colleagues, have sent a letter to President Obama, a Democrat, demanding answers on the swap and requesting the other 149 Guantanamo detainees remain in custody.

Proponents of the prisoner exchange say the Taliban members were not considered major members of the organization.

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