Coalition personnel mounted two operations last month to rescue members of a group of three hostages held by Iraq, but they didn't find them, a U.S. government official said Tuesday.

British civil engineer Kenneth Bigley (search) and U.S. engineers Eugene Armstrong (search) andJack Hensley (search) were the targets of the rescue. They were kidnapped from their homes in Baghdad on Sept. 16.

The first operation came before Sept. 20, when Armstrong is believed to have been beheaded by his captors, the U.S. official said, discussing sensitive operations only on the condition of anonymity. The second came after Armstrong's death but before that of Hensley, which was reported Sept. 21.

One cable TV report said U.S. forces found no signs of the three during either operation.

Bigley's killing was confirmed Sunday. Another U.S. official said there was credible information Bigley tried to escape with the help of one of his captors but was recaptured and quickly beheaded.

Tawhid and Jihad, lead by Jordanian terror mastermind Abu Musab al-Zarqawi, claimed responsibility for the abductions and killings.

More than 150 foreigners have been kidnapped in Iraq, some for ransom and others as leverage against the United States and its allies. Bigley was at least the 28th to be killed.