The test results were made public by Leicestershire Police after it was disclosed that an arm and a leg found in separate locations in Hertfordshire had belonged to a man.
The Herts and Leicestershire forces are working together to find out whether the human remains were all from the same person.
The results were released after a postmortem examination at Leicester Royal Infirmary, but forensic tests were continuing today to try to identify the dead man.
The examination was not able to establish a cause of death or to give a precise indication of how long the head had been in the field.
But police are trying to determine whether the body part belonged to the same man whose arm was discovered on farmland in Wheathampstead on Sunday, a week after his leg was found in a holdall about a 30-minute drive away in Cottered.
Tests have shown the leg belonged to a man between 5ft 6ins and 5ft 10ins tall. He is believed to have been white or Asian, but his DNA profile did not match any held on the National DNA Database.
Specialist search teams were continuing to scour the fields near to where farmer Tony Lomas made the grisly discovery, and other local inquiries were ongoing, said the force.