Although Mr Both is from York, he also has connections to Leeds and officers are appealing to people in both cities to keep an eye out for him and to call the police if they see him or know where he is now.
Detective Inspector Alan Rowan of York CID, said: We have carried out extensive enquiries over a number of weeks to find Mr Both and these searches will continue until we have found him.
To assist our enquiries, we are now asking for anyone who believes they have seen him or know of his current whereabouts to contact us with that information.
Anyone who has any information is asked to contact North Yorkshire Police on 101, select option 2 and ask for York CID.
If you have an immediate sighting of Mr Both, please contact the Force Control Room direct on 101.
If you prefer to remain anonymous, you can pass information to Crimestoppers on 0800 555 111.