A murder inquiry was launched when workmen discovered human remains wrapped in bin bags and a blanket in Hawthorn Lane, Warfield on 24 July.
Det Chief Insp Kevin Brown of Thames Valley Police told BBC Crimewatch the force had new information about a man believed to be connected to the case.
Mr Brown hopes the appeal will help to identify the body.
A post-mortem examination on the remains proved inconclusive but there was evidence of blunt force trauma to the head.
It suggested he could have been hit by a heavy object on either one or both sides of his head.
It is thought the body may have been placed in the field in Berkshire between 2008 and 2013, but he may have been killed elsewhere.
He is described as white, aged 30 to 40 years old and about 5ft 10in tall and of stocky build.
Mr Brown said the man had a "white and noticeable" smile and gave details of a "potentially very important breakthrough" after the victim's DNA had been analysed and linked with a woman from Lithuania.
He said that woman died in May, but detectives were appealing for information about her son, Aivaras Danilevicius, who is believed to have moved to the UK in 2004.
His mother reported him missing in 2008.
The computer generated image of the murder victim was created by experts at the University of Dundee.
A loose knitted blue and white striped jumper with a Turkish design label was recovered from the body.
The jumper is distributed in Europe and police want any information about people who have been known to wear a similar one.
A facial likeness of an unidentified man whose remains were found dumped in a ditch has been released.