Marcel has proven to be an unreliable witness. Unfortunately, Mac Brazel (the rancher who found the debris, and reported it) died long before people started really looking into the incident again.
However, we do know that he was taken to the Roswell base, and sworn to secrecy. Apparently he was very upset with the military's heavy-handed treatment, and wished he'd never reported anything.
One of the reporters who interviewed him, said he spoke of alien bodies. Obviously there's no way to corroborate that, since both he, and now the interviewer are dead. The sheriff who Brazel talked to who helped him get into contact with the military is also dead, though his descendants have made claims of confessions from his widow.