The good news: The Loch Ness Monster has been captured on sonar by an underwater robot operated by the British division of Norway's Kongsberg Maritime. The bad news: "Nessie" is a prop from a Sherlock Holmes film that sank in the loch in 1969. The monstrous model was long thought lost until it was discovered this week by the Munin Autonomous Underwater Vehicle (AUV) as part of an underwater survey of the loch for The Loch Ness Project and VisitScotland. There have been sporadic sightings of what is purported to be the Loch Ness Monster since the first recorded encounter by St Columba in 565 AD. After a supposed photograph was taken in 1933, public interest in some sort of large, dinosaur-like creature making its home in the Highlands skyrocketed, and in the decades since the loch has been subjected to sonar scans, submersible hunts, hydrophone surveys, and enough photographs taken above and below the surface to wallpaper the Grand Canyon.

Well that must have been weird: A marine robot scouring Loch Ness in Scotland detected something at the bottom of the lake, something that looked exactly the Loch Ness Monster. And it was indeed Nessie. Except, as Reuters reports, it was a long-lost 30-foot replica built for a 1970 Sherlock Holmes movie that sank during filming. "We have found a monster, but not the one many people might have expected," Nessie expert Adrian Shine tells the BBC. There's still hope for believers, though: The underwater robot from Norwegian company Kongsberg Maritime isn't finished mapping the lake, a project called Operation Groundtruth that will result in the first high-resolution survey of the body of water, reports Discovery. It should wrap up next week.

An underwater robot exploring Loch Ness has discovered a dark, monster-shaped mass in its depths. Disappointingly, tourism officials say the 30-foot (9-meter), object is not the fabled Loch Ness Monster, but a prop left over from a 1970 film. Billy Wilder's "The Private Life of Sherlock Holmes" puts the great detective on the trail of the monster -- which turns out to be a disguised submarine. A model of the submarine-monster sank during production to the bottom of the 750 foot (230 meter) -deep lake. Tourism body Visit Scotland is backing a survey of the Highlands lake by a marine robot to study its depths and see if there is any sign of the fabled monster, which helps attract hundreds of thousands of visitors a year to the region.

Fast-forward to 2016 and Kongsberg Maritime, a specialist in underwater positioning technology, has rediscovered the prop. The company was scanning with MUNIN, one of its many autonomous underwater robots, when it recorded an image of the 10 meter long replica. MUNIN uses a variety of sonar and camera equipment to produce high-resolution datasets at a depth of up to 1,500 meters. "Nessie" came up in one of its scans and Adrian Shine, who leads The Loch Ness Project, was able to confirm that it's the prop from The Private Life of Sherlock Holmes. "We can confidently say this is the model because of where it was found, the shape -- there is the neck and no humps -- and from the measurements," he told BBC News.

A 30ft (9m) model of the Loch Ness Monster built for a Sherlock Holmes movie has been found almost 50 years after it sank in the loch. The beast was created for the Billy Wilder-directed The Private Life of Sherlock Holmes, starring Sir Robert Stephens and Sir Christopher Lee. It has been seen for the first time in images captured by an underwater robot. Loch Ness expert Adrian Shine said the shape, measurements and location pointed to the object being the prop. The robot, operated by Norwegian company Kongsberg Maritime, is being used to investigate what lies in the depths of Loch Ness. VisitScotland and Mr Shine's The Loch Ness Project, which gathers scientific information on the loch's ecology and the potential for a monster, is supporting the survey.