Quantico, Va. ? Cpl. Wassef Ali Hassoun, the Marine who disappeared under mysterious circumstances while on duty in Iraq, insisted on Monday that he was captured by insurgents and that he is still a loyal Marine.

“I did not desert my post,” he told reporters outside Quantico Marine Corps Base. “I was captured and held against my will by anti-coalition forces for 19 days. This was a very difficult and challenging time for me.”

He did not answer any questions during his brief appearance. He was joined by his brother, who arrived from Utah.

“I would like to tell all the Marines as well as all those others serving in Iraq to keep their heads up and spirits high. Once a Marine, always a Marine, Semper Fi,” Hassoun said, invoking the Marine Corps motto, Latin for “always faithful.”

Marine spokesman Lt. Col. Dave Lapan said the Marine Corps was not in a position to confirm or refute Hassoun’s claim.

Hassoun, 24, of West Jordan, Utah, disappeared June 20 from his base near the troubled Iraqi city of Fallujah and turned up unharmed at the U.S. Embassy in Beirut on July 8. It remains unclear how he traveled from Iraq to Lebanon, where he was born and still has some relatives.

On June 27, Arab television showed a videotape of a blindfolded Hassoun, a sword hanging over his head. At one point during his disappearance, a group claiming to represent his captors announced that he had been beheaded after being lured from the base by a love affair.

The military is investigating whether the reported kidnapping was a hoax and whether the Muslim Hassoun deserted his unit.

Hassoun is in the midst of what the Marines call a “repatriation process” in which he is debriefed and given time to decompress and avoid the media spotlight, officials said.

The Naval Criminal Investigative Service is not expected to question Hassoun until his repatriation process is completed, the Marine Corps said.