VIDEO: CBS's 48 HOURS to Investigate Newlywed Disappearance, 5/11

CBS News Senior Correspondent John Miller leads a 48 Hours investigation into the disappearance of George Smith, a newlywed who vanished while on a honeymoon cruise in 2005. Miller's report uncovers questionable alibis, failed polygraphs and a provocative video that involves three men who last saw Smith alive.

The evidence will be featured on 48 HOURS: "Murder at Sea?" to be broadcast May 11, 2013 (10:00 PM, ET/PT) on the CBS Television Network. Get a sneak peek below!

"I have no doubt in my mind whatsoever that my son was murdered on that cruise ship," Smith's mother, Maureen, tells Miller. "There is so much evidence, it is overwhelming."

For nearly eight years, Maureen Smith has been seeking answers to what happened to her son, George. George Smith and his new wife, Jennifer Hagel Smith, set out on a cruise to celebrate their honeymoon. After a night of heavy drinking and gambling in the ship's casino and disco, George Smith vanished. A passenger in a neighboring room heard an argument on the Smith's balcony. Another heard furniture being moved. Jennifer Smith was later found passed out in a hallway on the ship. The next morning, passengers photographed a bloodstain on the overhang of the lifeboats.

The ship's captain describEd Smith's disappearance as a likely accident. Smith's body has never been found.

As Miller reports, the FBI has focused on four men who were the last to see him alive, but the case had gone nowhere. Seven and a half years later, Mike Jones, an attorney for the Smith family, now is trying to get the case moving again. Jones has gained access to Royal Caribbean's internal investigation into the Smith case. He later learned about the existence of a videotape in the possession of the FBI.

Jones says the videotape was recorded just hours after Smith went missing by three of the four men to last see the newlywed alive - Rusty Kofman, Zach and Greg Rozenberg. "They pass a video camera around filming themselves commenting about George's death in a very callous way," Smith tells Miller of the tape. "But the really incriminating statement is one of them stands up at the end of the tape and sort of hunches his shoulders and flashes gang signs and says, 'Told ya I was gangsta,' and in the context of the discussion about George's death, almost as if he's bragging about having done something to George." The man talking on the tape? "Greg Rozenberg," Jones says.

"It's ridiculously provocative," Jones says.

Lawyers for Rusty Kofman and Zach Rozenberg declined to comment about the tape. Greg Rozenberg's attorney says his client wasn't aware Smith was dead when the tape was made and was just making a stupid comment.

All four men say they had nothing to do with George Smith's death.

"The evidence is huge," says George Smith's sister, Bree. "Why hasn't someone been arrested?"

Miller's investigation into a case 48 Hours has been covering since 2006 features interviews with Smith's family, Mike Jones, a newlywed couple that spent time with George and Jennifer Smith in the days leading up to the disappearance, and former CIA case officer Phil Houston, an expert in detecting deception. 48 HOURS: "Murder at Sea?" is produced by Lourdes Aguiar and Pete Shaw. Jennifer Simpson Ashmawy is the field producer. Judy Tygard is the senior producer. Susan Zirinsky is the senior executive producer.