Spanish police have arrested a 29-year-old man on suspicion of failing to help an Irish tourist who drowned in the Canary Islands in the early hours of Sunday morning.
Details are still coming in but the dead woman is understood to have been on holiday in Lanzarote with her parents, the Daily Mail reports.
Elaine O'Donovan, 41, was spotted floating face down in the ocean off the popular beach of Playa Grande in Puerto de Carmen in the south-east of the island at 4am.
Police said O'Donovan appeared to have gone for a swim at the popular beach after a night out.
A Guardia Civil spokesman told the Irish Sun a group of people saw Ms O'Donovan arrive at the beach with a man.
He said: "They watched from a distance as the woman entered the water by herself to swim.
"The man was shouting something to her from the sand, but they couldn't hear what it was.
"He said something to her, (but) the woman paid him no attention and the man left.
"The next thing the other group saw was the woman floating face down in the water. Emergency services arrived and tried to resuscitate her, but they couldn't.
"Autopsy showed no sign of any violence, no marks, bruises or any other type of marks. Water was found in the lungs."
Before the arrival of an ambulance, doctors at the emergency help centre gave advice over the phone to the rescuers on the spot to try and revive her.
Medics who rushed to the scene also tried prolonged resuscitation but without success and O'Donovan was declared dead.
At the time, police had no idea of her identity and it took more than 24 hours to establish who she was. Officers searched the area for clues and eventually found her purse which revealed who she was.
Money was found in her purse and she was wearing an expensive watch so robbery has been ruled out. It is also understood that she had no signs of violence on her body.
The man helping police has only been identified by his initials of AS and is said to be of foreign nationality.
Witnesses have apparently reported seeing a man and woman on the beach at around 3am.
The 29-year-old man has been arrested on suspicion of failing to help someone who was in obvious trouble and could face prosecution for "being the presumed author of an alleged crime of omission of the duty."
He was arrested in Arrecife on Wednesday and is said to be known to the police. It is not known if he knew the woman or not.
Originally from Waterford, O'Donovan had been living in London for the past nine years, working for Butyl Products Ltd which supplies sanitation equipment to aid agencies.
Pals also paid tribute to her on her Facebook page.
One friend wrote: "Beautiful lady inside and out - always smiling."
Investigations are continuing.