A Saudi prince who beat and strangled his servant to death at the culmination of a campaign of "sadistic" abuse is facing a life sentence after being convicted of murder.

Saud Abdulaziz bin Nasser al Saud, a grandson of the billionaire king of Saudi Arabia, was found guilty at the Old Bailey of killing Bandar Abdulaziz at their five-star hotel suite in central London.

Saud had been drinking champagne and cocktails when he bit the 32-year-old hard on both cheeks during the attack in February. The pair had just returned from a Valentine's night out.

The 34-year-old prince was found guilty of murder today after the jury had deliberated for an hour and 35 minutes. He showed no reaction as the verdict was returned.

The court had heard that the murder of Abdulaziz was the final act in a "deeply abusive" master-servant relationship in which the prince carried out frequent attacks on his aide "for his own personal gratification".

Jurors were told that by the early hours of 15 February, Abdulaziz was so worn down and injured – having suffered a "cauliflower" ear and swollen eye from previous assaults – that he let Saud kill him without a fight.

The prince then spent hours on the phone to a mysterious contact in Saudi Arabia trying to decide how to cover up what he had done.

He ordered two glasses of milk and bottled water on room service as he set about dragging the body into the bed and trying to clean up the blood.

It was only about 12 hours later, after a chauffeur had received a call from Saudi Arabia telling him to go to the £259-a-night Landmark hotel, that the body was discovered in room 312.

The prince claimed he had woken in the afternoon to find he could not revive his friend – by then stiff with rigor mortis – and explained his injuries by saying he had been attacked and robbed of €3,000 in London's Edgware Road a few weeks before.

Detectives took him to the area to try to retrace the route, but as they did so, other officers who were reviewing CCTV at the hotel found footage of Saud mercilessly attacking his aide in a lift on 22 January.

When he was then taken to Paddington Green police station and arrested, Saudi officials tried to claim he had diplomatic immunity, but this was scotched by a check of Foreign Office records.

Saud tried to cover up the true nature of his relationship with his servant, claiming they were "friends and equals", but a porter at the Marylebone hotel where they had stayed said Abdulaziz was treated "like a slave".

The prince also claimed he was heterosexual and had a girlfriend in Saudi Arabia, but he had booked appointments with at least two male escorts and one gay masseur, and looked at hundreds of images of men on gay websites.

Photographs of Abdulaziz in "compromising" positions were found on his phone.

Saud had denied killing his servant until shortly before the trial, before finally admitting that he had caused his death. Jurors rejected a claim by his barrister, John Kelsey-Fry QC, that Saud was guilty only of manslaughter.

The prince was convicted of murder and a second count of grievous bodily harm with intent relating to the attack in the lift.

Sources said detectives in the case had received little help after requests for information were sent through Interpol to their Saudi colleagues.

Saud's lawyers also failed in a last-ditch attempt to stop details of his encounters with male escorts being revealed during the trial. In a sign of the anxiety about his sexuality becoming public, the prince's lawyers had initially argued that the legal argument about the escorts should be held behind closed doors.

Kelsey-Fry said Saud had already faced abuse from Islamic fundamentalists being held alongside him at Belmarsh prison. The court heard that homosexuality remains a capital offence in Saudi Arabia, and the country in which the acts take place has little relevance to prosecution under the country's sharia law.

Outside court, Detective Chief Inspector John McFarlane said: "The defendant used his position of power, money and authority over his victim Bandar to abuse him over an extended period of time.

"CCTV recovered clearly shows Bandar was subjected to assaults in the hotel. The injuries which were noted by the pathologist clearly show Bandar was the victim of many more assaults over an extended period of time. This verdict clearly shows no-one, regardless of their position, is above the law."

Saud was remanded in custody to be sentenced tomorrow.