HOUSTON – New details are coming out of the investigation of a woman who went overboard on the Carnival Liberty cruise ship over the weekend.

Samantha Broberg's disappearance remains a mystery. There is no definitive answer as to what exactly happened in the moments leading up to her falling off the ship.

The FBI is now investigating, and several passengers on the ship are sharing some disturbing details.

A picture of a section of the 10th deck on the Liberty where the 33-year-old Broberg apparently went overboard has surfaced, but Carnival says the reddish stain in the picture is from a spilled red-colored cocktail.

The area is roped off and Derrick Lewis said he was standing there when he said investigators found a knife nearby.

"They found a knife, in the trash, right by the incident. I was standing right there," Lewis said.

Carnival Cruise Lines said Broberg disappeared late Friday.

After searching the ship and going over surveillance video, they discovered she had gone overboard.

"They put everyone on lockdown, made everyone go to their rooms and they came through and did a ship wide search," said passenger Ariel Lane.

Footage shows Broberg sitting on top of the railing and then falling backwards.

Passengers said those railings are about 5 feet tall and to get up there you have to climb.

"The railings are all high, so she would have to climb up to fall over, unless she was pushed, so it really doesn't make a lot of sense to people who are talking about it," passenger Jordan Lee said.

Passengers said when Broberg went overboard, and they were told to stay in their rooms.

"We were put in our rooms for awhile while they searched the ship and then we were told that she had gone overboard," Lee said.

Carnival Cruise Lines said, "This is a terrible sad and tragic event. As far as foul play, there is none suspected and the camera footage shows no indication of foul play. There is no merit to the theory put forth by these individuals you have been talking with."

The FBI said this is a death investigation, but did not comment on the knife or if there was any foul play.

Passenger says this is the 10th deck railing Broberg fell from Carnival Liberty Cruiseship(on the other side)@KPRC2 pic.twitter.com/SEYsINIJ2x — Sofía Ojeda (@KPRC2Sofia) May 16, 2016

.@FBIHouston is working with @CarnivalCruise to investigate a passenger who went overboard. Standard procedure. pic.twitter.com/k2nqvt9tQK — Jace Larson (@jacelarson) May 16, 2016

@CarnivalCruise says in part "Footage shows no indication of foul play. Stain is not blood, but a spill of some sort." @KPRC2 — Sofía Ojeda (@KPRC2Sofia) May 16, 2016