On 31 January, Casement signed on loan for Linfield until the end of the season. On 4 May 2010, he was informed along with three other players that he was no longer wanted by Dundee and was free to look for another club. On 8 May 2012, it was confirmed Casement had signed a three-year contract with Portadown. On 26 July 2016, it was announced that Portadown had accepted a bid in the region of £20,000 for Casement and it was announced later that he would be rejoining the "Blues" on a two-year contract.