Williams' family argued that police interfered with DNA that could have helped solve the case, and fingerprints left at the scene were wiped off as part of a cover-up.
Inconclusive fragments of DNA components from at least two people were found on the bag but did not lead to any suspects that police identified publicly.
The coroner reported no injuries on Williams's body and no signs that he had been involved in a struggle. He also tested negative for alcohol and common recreational drugs.
Williams was buried at Ynys Wen Cemetery in Valley, Anglesey, on September 26, 2010, following a private funeral service at Bethel Chapel in Holyhead attended by his family, friends, and former colleagues in the intelligence services.