The man's body was found in a field off White Moss Road South, near the M58 in Skelmersdale, at 11am yesterday (Tuesday).
Lancashire Police were called to the scene and a white tent was erected in the field, where CSI and forensics worked to establish the man's identity and cause of death.
Though formal identification is yet to take place, police say his next of kin has been informed.
Lancashire Police said the investigation is now being led by Greater Manchester Police, who today arrested three men in connection with his death.
Two men - aged 48 and 51 - have been arrested on suspicion of kidnap and murder, and a 29-year-old man has also been arrested on suspicion of conspiracy to kidnap and murder.
They remain in police custody for questioning.
Greater Manchester Police (GMP) said the incident has been referred to the Professional Standards Branch and the Independent Office for Police Conduct.
It has not provided precise details on the reason for the referrals, but the force says it is "in line with normal procedure" after it received a report of "suspicious circumstances" the previous day.
It said the report was received after a missing person investigation was launched on Saturday (February 19).
Detective Chief Inspector Carl Jones, of GMP's Major Incident Team, said: "Firstly, our thoughts are with the victim's loved ones at this devastating time.
"Fast-paced enquiries are ongoing and we are working closely with Lancashire Police to establish the full circumstances surrounding this man's death and identify those responsible.
"I can reassure members of the public that, although our investigation is continuing, we do not believe there is any threat or risk to the wider community."
Anyone with information should contact Greater Manchester Police via gmp.police.uk or 101.
Information can also be shared anonymously via, the independent charity, Crimestoppers on 0800 555 111.
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