This Hospital Porter was killed by a Weevil that had gone rogue in Cardiff and come up from the sewers. The Weevil had been contained on a floor of the hospital by Torchwood - with the cover story of a chemical leak given to isolate the ward. Gwen Cooper however, in an attempt to find out more about Torchwood, broke the seal and was followed shortly after by the porter. Believing the Weevil to be a man in a mask, the porter got close enough to have his throat ripped out.
Gwen later discovered that Torchwood covered his body by retrospectively changing the work rotas for that day and planting a false alibi stating that he was seen leaving the hospital giving him a further 48 hours before his body was pulled out of the docks the next Tuesday night, meaning he was 'missing' for three days. (TW: Everything Changes)