"This is not going to go away, we will not stop until you are arrested" - that is the stark message from North Yorkshire Police to Robert Henry Foster.
Foster, 22, is wanted in connection with a serious assault which occurred at Seamer Caravan Site, in the Stokesley area, at about 5pm on Friday 22 July 2011.
The 43-year-old victim is his wife Natalie's father who has undergone surgery at James Cook University Hospital on Teesside. He is in a serious but stable condition.
Two men appeared at Northallerton Magistrates' Court on 25 July 2011 charged with wounding with intent. They were remanded in custody and both were committed to appear at Teesside Crown Court on Thursday.
Also, following an intense and high profile media appeal, Natalie Foster, 18, and their seven-month-old son Robert, were confirmed to be safe and well after they attended Northallerton Police Station late on Sunday evening. There had been considerable concern for their safety after there had been no contact since Friday.
Extensive police enquiries to trace Foster remain ongoing.
Detective Chief Inspector Kerrin Smith, who is leading the North Yorkshire Police investigation, said: "It is time for Robert Foster to do the right thing and hand himself in to the police.
"He needs to realise that he is involved in a very serious matter in which two people have already appeared at court.
"The police will not let up until he is arrested and brought into custody. This is not going to go away.
"Robert, the choice is yours now. You can make things easier for yourself and come forward to assist the investigation. Or you can hide away and wait for the net to close ever tighter around you."
Anyone with information that can help to locate Robert Henry Foster is urged to contact North Yorkshire Police on 0845 60 60 24 7, quoting the reference number 12110121906.
Information can also be passed on anonymously to the independent charity Crimestoppers by calling 0800 555 111.
5pm - 25 July 2011