An Iraqi insurgent group said Thursday in an Internet posting that it killed a U.S. security consultant it had taken hostage. The claim's authenticity could not be immediately verified. The Islamic Army in Iraq said it had killed "the American security consultant for the Housing Ministry," after the United States failed to respond to its demand of the release of Iraqi prisoners. A video issued by the group was aired Tuesday on the Arab television station Al-Jazeera showing the hostage — identified as Ronald Schulz, 40, an industrial electrician from Alaska — sitting with his hands tied behind his back. Thursday's statement, posted on an Islamic militant Web forum, did not identify the hostage and provided no evidence he had been killed, but said pictures of the slaying would be released later. Schulz graduated from Jamestown, N.D., High School in 1983, then joined the Marines. His brother, Ed, said he served in the Marine Corps from 1984 to 1991 and after his discharge, moved to the Anchorage, Alaska, suburb of Eagle River.