Police are appealing for information after burglars targeted six homes in Rustington and Littlehampton within the space of a week.
The burglaries all happened between the evening of Sunday, August 10, and the morning of Wednesday, August 13.
The most recent offence happened in The Martlets, Rustington, between midnight and 8am on August 13, when intruders got into the house and stole a gold Rolex Submariner watch worth around £18,000.
They also took two iPhones, a red Olympus Stylus VG-180 camera, a black handbag containing around £130 and a black leather wallet containing more than £1,000.
The crime is being linked to two burglaries in The Gilberts and two attempted burglaries in The Gilberts and Sea Lane in Rustington, late on 10 August or early 11 August.
A mobile phone and a laptop were stolen during the incidents.
The same people are also believed to be responsible for a burglary in Woodlands Road, Littlehampton, late on August 11 or early on August 12.
In that incident a thief used an unlocked window to get into a house and steal a wallet.
Operation Magpie was launched by Sussex Police to tackle burglary across the county.
Detective Constable Pippa Hannard said: “We believe the same burglar or burglars are responsible for each of the incidents and are keen to speak to anyone who was in the area and who saw or heard anything suspicious.
“The owner of the stolen Rolex watch has offered a £1,000 reward for information that leads to its return, and the arrest, and conviction, of whoever is responsible.
“If you know anything at all, please contact us.”
Anyone with information about any of the burglaries should call 101 quoting serial 363 of 13/08, email firstname.lastname@example.org or call the independent charity Crimestoppers anonymously on 0800 555111.