Police have put up a £1,000 reward for anyone who can help find armed robbery suspect Sean Tierney.
The 27-year-old is wanted for questioning by detectives over the robbery at Maxted's newsagents in Rustington on May 14.
Shortly after 5pm a man wearing a crash helmet with the visor down walked into the Worthing Road shop carrying a gun and a drawstring bag.
He walked up to the till and ordered staff to hand over money before escaping with a quantity of cash.
Police would like to speak to Sean Tierney, who has links to Worthing and Littlehampton, in connection with the robbery.
A £1,000 reward has been put up for whoever gives officers the information that leads to the arrest and conviction of Tierney.
Detective Inspector Dave Wardley-Wilkins said: "We have been looking for Sean Tierney for more than a week now but have been unable to trace him so we are hoping that the offer of a reward might persuade someone to get in touch with us.
"If anyone knows where he is or where he could be I would urge them to contact us immediately.
"If you see him do not approach him but instead call 999 please."
Anyone with information should call 101 quoting serial 1213 of 14/5, email firstname.lastname@example.org or call the independent charity Crimestoppers anonymously on 0800 555111.