In the hottest summer Spain has had in 40 years, some experts fear she may have collapsed after leaving the cool air conditioned rooms of her home into the mid-day sun.
The star was found dead by her eldest son Bobby, 44, last weekend. She was at her luxury home in Marbella when the incident happened, and Bobby had to break down her bedroom door to reach her.
Investigators are now looking into whether her collapse was caused by a dizzy spell - perhaps from the heat.
Celebrities from across the world have paid tribute to the late star, who presented the infamous Blind Date until 2013.
Cliff Richard, who had planned to meet up with Cilla tho week, paid his respects with a touching message in The Sun, in which he confesses: ‘Cill, I love you.’
It is known that Cilla went upstairs for a siesta on 1.30PM on Saturday, but when she failed to emerged from her bedroom hours later, her son knocked on the door.
After getting no response, Bobby smashed his way into the room and found her lying on her back on the terrace.