Durham Police say 30 officers are now working full-time on the investigation into the death of a former solicitor.
Peter Maine, 56, was found with stab wounds on a path opposite the running track at Maiden Castle Sports Centre at around 8am on September 1.
Specialist search teams have been scouring the area, while officers spent this morning distributing posters of Mr Maine in the local vicinity. They are also gathering CCTV footage in the hope of gaining further information regarding his movements before his death.
Anyone with information regarding Mr Maine's death is being asked to contact Durham Police on 101.
More top news
The constituency of Washington and Sunderland West includes the UK's largest car plant, which was opened by Nissan in 1984.
This seat was formed prior to the 2010 General Election, taking in Sunderland city centre and the Ryhope area to the south.
The constituency of Stockton South includes relatively affluent areas like Yarm and Eaglescliffe.