Further searches are taking place this weekend off the north Mayo coast as the investigation into the deaths of four Coast Guard crew members in a helicopter crash last March continues.

The crew of Rescue 116 were lost when their helicopter collided with Blackrock Island on 14 March.

The bodies of Captain Dara Fitzpatrick and Captain Mark Duffy were recovered in the days following the accident, but the search for Winch Operator Paul Ormsby and Winch Man Ciarán Smith is ongoing.

A search off Blackrock resumed earlier this week when garda divers oversaw a trawling operation around the island for a number of days.

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That has now concluded and the next phase of the operation will see specialist underwater cameras deployed to examine areas of interest.

The Garda Superintendent leading the investigation, Tony Healy, said the latest searches are focusing on areas that were not subject to detailed surveys during the earlier stages of the inquiry.

The Irish Lights vessel, Granuaile, has returned to Blacksod Bay and will be used as a platform for operations by the Marine Institute's Holland I remotely operated vehicle this weekend.

During the week, sonar surveys of the waters around Blackrock were carried out.

Data gathered during these investigations will be used by the Marine Institute to examine a number of areas beneath the sea surface.

The ROV can operate at depths of up to three kilometres but it is understood the primary focus is on certain areas between the surface and the sea bed.

In addition to the work being carried out close to the island, around 25 divers from the Irish Underwater Council are travelling to Mayo to take part in searches around the Inishkea and Duvillaun Islands in Blacksod Bay.

These are located to the northeast of Blackrock and will be surveyed for any debris that may have been disturbed as a result of the trawls carried out around the crash site this week.

Teams of divers from Donegal, Mayo and Galway will take part in the operation, which will be led by members of the Garda Sub-Aqua Unit.