A non-league club faces suspension by the Football Association from all competitions for refusing to pay an ex-player jailed on a robbery charge.
Sestanovich played one pre-season friendly for Grays before his arrest
Grays Athletic FC terminated Ashley Sestanovich's contract before his conviction for conspiracy to rob.
Grays have been given 14 days by the FA to pay Sestanovich £14,000 for the five months up to his conviction.
He was jailed for eight years. Two other men were jailed for life for shooting a man dead during the raid.
An FA disciplinary hearing ordered Grays to pay Sestanovich five months' wages, in June, last year, after ruling they were in breach of FA regulations.
The club must also pay a £500 fine and the hearing's costs.
If they fail to do so, the south Essex club will be suspended from all football.
Grays have been involved in a counterclaim against Sestanovich who played one pre-season friendly for the club before his arrest.
The club claim that Sestanovich originally told them he was being held on remand for motoring offences, but once the nature of the charges became known they served him with 14 days' notice.
His conviction related to a robbery in Streatham, London, in 2005 in which Thomas Fahey was murdered.
'Shot in cold-blood'
Grays chairman Mike Woodward said: "I am bitterly disappointed in the FA's judgment, all they seem to want to do is take money from football clubs.
"We are being forced to pay approximately £14,000 to a player who only had three training sessions and 20 minutes in a pre-season friendly due to his involvement in a heinous crime which saw a young father shot in cold-blood.
"Unfortunately my principles will not allow me to pay this money from either my own pocket, or from the club's, and the directors are of the same opinion.
"I feel sorry for the supporters of this club but I hope that you will back me on this decision."
The FA said because Sestanovich was arrested after he signed for Grays, the club were obliged to honour his contract until he was actually convicted of an offence, under contract law.
Sestanovich also doubled for former Arsenal star Thierry Henry's TV advertisements for clothing company Nike.