PORTLAND (AP) – The Coast Guard announced Tuesday it located the sunken fishing boat Lady Luck in 530 feet of water and used a remote-control submersible to examine the wreckage, found about 20 miles southeast of Portland.

The Coast Guard took the unusual step of examining the boat on the ocean floor because there’s so little evidence as to why the trawler from Newburyport, Mass., sank either late on Jan. 31 or early on Feb. 1.

Rescuers responding to an automated distress signal found only debris and an oil slick. The two crew members are missing and presumed drowned.

“The video that was gathered will help investigators learn what happened,” said Coast Guard Lt. Connie Braesch in South Portland.

The Coast Guard obtained the video footage on March 13 with a tethered submersible. The Coast Guard didn’t disclose the news until Tuesday, after the families of crew members were notified and briefed, Braesch said.

Lady Luck was docked in Portland before it departed on Jan. 31 for Gloucester, Mass. But it didn’t make it far.

The first and only sign of trouble was an automated distress beacon that sounded at 2:15 a.m. Rescuers found the radio beacon floating in the water, but there was no sign of the 52-foot trawler or its crew.

The Coast Guard launched an air-and-sea search, assisted by fishing boats, but the boat’s skipper, Sean Cone, 24, of North Andover, Mass., and crewman Dan Miller, 21, of North Hampton, N.H., were never found.

The Coast Guard in Boston has a remote-control VideoRay device capable of capturing images in 500 feet of water, but three VideoRay workers brought another device capable of going as deep as 1,000 feet to film the Lady Luck.

The video camera captured detailed footage of the boat but it didn’t detect the crew members’ bodies, said Chris Gibson from Pennsylvania-based Video Ray.

Investigators hope the video footage will help to narrow the list of possible causes as investigators continue to piece together what happened. Already, it helped dispel some theories of what might have happened, said Gibson, who declined to elaborate.

The Coast Guard also hopes the footage will help to explain why mandatory vessel safety equipment was not found by rescuers. The boat was equipped with a life raft that was supposed to automatically deploy during a sinking.

Another concern of the Coast Guard is whether the automated distress beacon, which is designed to float away from a boat, worked properly.

The last known location of the Lady Luck through the federal fishery agency’s Vessel Monitoring System was at 10 p.m. on Jan. 31. The Emergency Position-Indicating Radio Beacon didn’t sound until 2:15 a.m. at the same location.

Thus, it’s possible that the Lady Luck sank earlier and that the radio beacon didn’t work properly, possibly delaying rescuers. But it’s also possible that there was a problem with the Vessel Monitoring System, mandated for all commercial fishing boats.

The Coast Guard had boarded the vessel on Dec. 15 and it had appropriate safety gear including survival suits, in addition to the raft and radio beacon, Braesch said.

The Lady Luck was the second New England fishing boat to go down over the span of a week.

The New Bedford, Mass.,-based fishing vessel Lady of Grace sank in Nantucket Sound, where the wreckage was located. One crew member’s body has been recovered, while the other three were missing and presumed dead.