Cooper died aged 54 on Monday died after collapsing at the weekend.
Police Scotland said they are not treating the cause of his fatal injuries as suspicious but have appealed for potential witnesses to come forward.
The foursome got into the cab in Aberdeen's Union Street around 12.30 on Sunday morning.
"Police inquiries were ongoing throughout the night to establish the full circumstances, however the incident does not appear to be suspicious".
Egyptian lawyer files €1 billion lawsuit against Ramos for Salah challenge
The really disgusting element is one again Sergio Ramos trying to roll over on to the player's arm with his full body weight. The 25-year-old left the field in tears before Real Madrid's 3-1 victory in Kiev on Saturday night.
Nabil Fekir interested in move to Liverpool
Fekir insists a move to Liverpool is " not close " as speculation mounts over the Lyon playmaker's future. He said: "I do not have a rendezvous with the Liverpool directors".
Malaysia PM to drop high-speed rail project with Singapore - FT
The Prime Minister said that the government had to talk to Singapore about it and the compensation that needed to be paid. That's almost double the 687 billion ringgit federal government debt number disclosed by the former administration.
Cooper was a mainstay of Sir Alex Ferguson's Dons side which was a driving force in Scottish football during the 1980s, and in 1983 claimed European Cup Winners' Cup success followed by the European Super Cup.
Hartlepool United have sent a message of support, the club tweeted: "The thoughts and best wishes of everyone connected with Hartlepool United are with former boss Neale Cooper after hearing the news he is in hospital". He also won two league winners' medals following the Aberdeen's championship triumphs of 1984 and 1985, while he won the Scottish Cup four times and League Cup once.
Cooper played for Aston Villa, Rangers, Reading, Dunfermline Athletic and Ross County as well as Aberdeen.
At County, he moved into management, initially on a player-manager basis, with two spells at Hartlepool, a brief stint at Gillingham and another at Peterhead following.