In Aston Clinton at around 4:30pm on Monday 9 May on Tring Hill, a man was repeatedly punched and kicked in the head.
The victim a man in his 50s was pummeled, after he approached the offender, informing him he was trespassing on private land.
Investigating officer, PC Graham Gray, based at Aylesbury police station, said: “I am appealing for witnesses to this incident, or to anyone with information relating to it.
“Anyone who has information on this, or thinks they recognise the person depicted in the E-fit, is asked to report this matter online, or call 101 quoting reference number 43220200476.
“Alternatively, you can call independent charity Crimestoppers on 0800 555 111 for 100% anonymity.”
Editor’s note: A previous version of this article stated the attack happened on Tuesday 10 May, the article has been amended to show the correct date of Monday 9 May.