Mystery over woman's murder on Alaska cruise ship

Incident happened aboard the Emerald Princess cruise ship (file picture)

A man has been arrested in connection to the murder of a woman aboard a cruise ship off the coast of Alaska, police say, in what has been described as a "domestic disturbance".

The victim has been identified as 39-year-old Kristy Manzanares, from the US state of Utah. Witnesses say she was travelling with her children.

The death on Tuesday night triggered a lockdown of the 3,400-passenger ship.

Authorities were expected to announce charges on the case on Thursday.

The FBI is investigating the death because it occurred in US waters.

The Emerald Princess, operated by Princess Cruises, had departed from Seattle on Sunday for a week-long trip.

Kristy Manzanares had been travelling with a large group, including her children, according to witnesses.

After the death, the ship was diverted to the city of Juneau, in Alaska, and passengers were forced by investigators to remain on board for more than eight hours.

Witnesses say that the incident was described by crew members as "a domestic disturbance".

Passengers told CBS News that a "murder mystery" theme dinner had been taking place when the incident occurred, and several passengers first confused the crime for a hoax.

"One of the little girls from that room came running out, calling for help, that her parents had been in a fight," one passenger told CBS News.

"She sounded pretty desperate, but the crew came up as quickly as they could", he said, adding that the incident occurred on the 9th floor of the 19-deck ship.

Other witnesses described seeing a bloody man threatening to jump off the ship.