Michael McInnes, 23, was locked up for six years in 2010 for attacking Kevin McNee in Coatbridge, North Lanarkshire, leaving him with permanent disabilities.
Having been granted temporary home release from HMP Castle Huntly, near Dundee, to an address in Glasgow, McInnes was expected to go back to prison on Wednesday, December 4.
But he has still not returned and police are appealing for information as to his whereabouts. McInnes is believed to frequent the Glenluce area in Wigtownshire and Bellshill in North Lanarkshire. A police spokesman said yesterday: "He is six foot tall, with short brown hair and has a star tattoo on his neck behind both ears.
"Anyone who has seen him, or who knows where he is, should call 101, or speak to any police officer."