Officers received an automated message from a mobile phone at 10.18pm that night to say there had been a crash near Straiton but, despite thorough searches, nothing was found.
Then at around 7.35am the following day, police said a red, blue and white Honda motorcycle was found off the B741, with the 21-year-old motorcyclist being pronounced dead at the scene.
Police Scotland said extensive inquiries are under way and a report will be submitted to the procurator fiscal, although no other vehicles were thought to be involved.
Inspector Craig Beaver, from Ayrshire road policing unit, asked for anyone with information or who had seen the bike being ridden by Mr Sturgeon in the surrounding area to contact police.
He said: “Our inquiries into the circumstances of what happened are under way and our thoughts are with Darrel’s family and friends.
“I would appeal to anyone who may have seen a red, blue and white Honda CBR600F motorcycle in Crosshill, Maybole and Straiton areas.
“I’m also appealing to anyone who witnessed the crash or who may have dash-cam footage to contact us as soon as possible, as you may have captured something that could assist our investigation.”
Anyone with information can call Police Scotland on 101, quoting incident number 4082 of November 8 2023.