The trial has left a major question mark over security at the Cumberland, a large hotel conveniently close to one of London's major shopping streets and a popular destination for holidaymakers from the UAE and the rest of the Middle East.
During his evidence, Spence told the jury that he regularly sneaked into the Cumberland Hotel to look for food and a place to sleep.
On the night of the attack, he told the jury, he had left the flat of an acquaintance in north London after an argument and "ended up going to the Cumberland". That, he added, was "where I sleep if I don't have anywhere to sleep".
He said he was in the habit of prowling the hotel's floors, scavenging food from trays left outside guests' rooms and bedding down in the maids' cleaning closets.
Because the Cumberland's lifts are not protected by a key-card system, common in many other comparable London hotels, Spence was able to use the lifts in the lobby to access the hotel's guest floors with ease.
By July, three months after the horrific attack, the lifts remained unprotected and a National reporter was able to enter the 1,000-room Cumberland unchallenged and trace Spence's footsteps to the seventh floor, where his victims were staying.
At the time, a spokesman for the Guoman group, which runs the Cumberland and three other central London hotels, told The National it had as no plans to instal a security system in its lifts.
Asked if the group had reviewed security at the Cumberland at all after the attack, the spokesman's replied: "What we didn't do was add any more security to the hotel. We felt that the security was totally adequate."
He added: "You can't build a policy on the basis of one incident."
As part of their investigation, police seized more than 330 hours of footage from 200 cameras in and around the hotel. CCTV video footage released by the Metropolitan Police shows Spence entering the hotel by an unlocked side door in the small hours of Sunday, April 6.
He then took the lift to the fifth floor before using the stairs to reach the seventh. There, finding the door to the women's room ajar, Spence carried out his appalling attack.
A spokesman for the hotel said the entrance Spence had used was the only one open at that time of night. But, despite it being "situated close to the presence of security personnel, the night concierge and the night porters on the ground floor", no-one had challenged Spence.
"There were other guests present in the lobby area as well as a number of members of staff at the front desk immediately opposite the door," said the spokesman. But, despite the accused's admission that he had spent the day taking crack and heroin, there had been "nothing in Spence's appearance or demeanour that would point him out as someone with criminal intent".
The hotel group insisted that Spence's suggestion that he had been able to come and go at the Cumberland at will "does not stand up to scrutiny" and had been invented to bolster his defence that the attack had been unplanned.
"The assailant's evidence was self-serving and untruthful," said the spokesman. "Our linen-cupboards are self-locking so cannot be accessed overnight and our room-service trays are removed promptly.
"We believe his sole purpose was to steal valuable items from guests. However, all our bedroom doors are heavy-duty, fire-resistant and equipped with self-closing mechanisms to amply provide for guest safety, as are our linen cupboards."
The "desperately sad truth", he added, was that "Mr Spence could only access the bedroom because the door was left open".
The group was "relieved for the sisters and their family that the trial has ended and justice has been done. Our thoughts remain with them for their continued recovery after an unimaginable ordeal."
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