The search for missing footballer Emiliano Sala and pilot David Ibbotson has been called off after rescuers failed to find their plane.
Cardiff City's Argentine striker, 28, and Mr Ibbotson, from Crowle, Lincolnshire, were on the aircraft that disappeared from radar on Monday.
After three days of scouring the English Channel, authorities made the decision to abandon the search.
But Sala's sister Romina pleaded with rescuers to keep looking for him.
Guernsey Police tweeted at 15:15 GMT to say rescuers were "no longer actively searching" for the plane.
Harbourmaster Capt David Barker said the chances of survival were "extremely remote".
"We reviewed all the information available to us, as well as knowing what emergency equipment was on board, and have taken the difficult decision to end the search," he added.
He said: "I understand Emiliano Sala's family are not content with the decision to stop the search and I fully understand that.
"I'm absolutely confident that we couldn't have done any more."
As the news was announced, Sala's sister Romina pleaded with the authorities to keep searching, saying: "I know in my heart Emiliano is still alive."
She said: "Please, please, please don't stop the search. We understand the effort but please don't stop the search.
"For us, they are still alive. It is difficult to express our feelings at the moment because everything is really hard.
"Emiliano is a fighter. I'm asking you please, don't stop looking for them. It's been three days and I've still got hope that they're alive.
"It's terrible, it's desperate not knowing anything. We don't have certainty of anything."
His former club FC Nantes also tweeted appealing to the police to continue the search.
Responding to the search being called off, Cardiff City owner Vincent Tan said: "We were looking forward to providing Emiliano with the next step in his life and career.
"Those who met Emiliano described a good-natured and humble young man who was eager to impress in the Premier League.
"The response from the football community has been truly touching and we place on record our sincere thanks to those who have sent messages of support.
"We also thank everyone involved with the search and rescue operation, and continue to pray for Emiliano, David Ibbotson and their families."
Capt Barker said the depth of the sea where the plane had last contact was about 100m and it would remain a missing persons case for the police.
"Despite best efforts of air and search assets from the Channel Islands, UK and France... we have been unable to find any trace of the aircraft, the pilot or the passenger," he added.
Sala became Cardiff City's record signing on Saturday, joining from Ligue 1 club Nantes for a fee of £15m.
He had returned to the French city to say a final farewell to his former teammates before taking the plane back to the Welsh capital.
The single-engine plane carrying Sala and Mr Ibbotson left Nantes, north-west France, at 19:15 on Monday and had been flying at 5,000ft (1,500m) over the Channel Islands when Mr Ibbotson contacted air traffic control and requested to descend.
It lost contact while at 2,300ft (700m) and disappeared off radar near the Casquets lighthouse, infamous among mariners as the site of many shipwrecks, eight miles (13km) north-west of Alderney.
Sala reportedly sent a WhatsApp voice message before the flight. Sounding conversational and jokey, he said he was "so scared" and: "I'm on a plane that seems like it is breaking apart."
Rescue crews have searched about 1,700 square miles of land and sea in the Channel Islands in the past three days, covering Burhou, the Casquets, Alderney, the north coast of the Cherbourg Peninsula, north coast of Jersey and Sark.