Forensic officers are currently searching a King's Lynn property following the arrest of two men on suspicion of murder.
Armed police officers brought traffic to a standstill when they arrested a 25-year-old and 34-year-old in Saturday Market Place at the junction with High Street at 12noon.
The men were then taken to Boston police station in Lincolnshire to be interviewed on suspicion of the murder of Jan Pawel Stochnialek.
Mr Stochnialek's body was discovered in the South Forty Foot Drain in Boston on Wednesday, January 25. A 23-year-old man has also been arrested in Manchester in connection with the murder.
King's Lynn Superintendent David Marshall said: 'Due to the nature of the operation, a number of armed units were deployed to ensure a swift outcome.
'Public safety was at the heart of our planning and at no time was anyone put at risk.'
Lincolnshire Police is still appealing for anyone with information about the movements of Mr Stochnialek from Christmas Eve onwards to contact them on 101, quoting incident number 163 of January 25.
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