A 32-year-old man has been charged with assaulting and falsely imprisoning 23-year-old Patryk Krupa whose body was discovered in the River Shannon near Athlone on Friday night.

Lezek Scychulec, with an address at 14 Drinan, Ballymahon, Co Longford, appeared at a special sitting of the District Court in Athlone.

Mr Scychulec was also charged with threatening to kill or cause serious harm to Ewa Krasinska at Athlone Garda Station yesterday.

The 32-year-old was remanded in custody to appear again at a sitting of the District Court in Cloverhill on 27 June.

Mr Scychulec was heckled by a small crowd, including members of the Polish community, as he entered and left the court building.

The accused was also verbally abused by relatives of Mr Krupa in court and the judge had left the bench.

Mr Krupa's body was discovered partially submerged in an area known as Bogginfin at around 8.25pm on Friday.

Four men have been arrested in connection with the murder, two remain in custody.

Two men were released without charge overnight and files will be prepared for the Director of Public Prosecutions.

A post-mortem examination was due to be carried out on the body at University Hospital Galway yesterday.

The results of that examination have not been released.

Gardaí have appealed for witnesses or to anyone who can assist with the investigation to contact Athlone Garda Station on 090 6498550, the Garda Confidential Telephone Line 1800 666 111 or any garda station.