Mallard had been convicted of the murder of Pamela Lawrence, a business proprietor, who was killed at her shop, on 23 May 1994. The evidence used in Mallard's trial was scanty and obscure, and it was later revealed that police withheld vital information from his defence team. Almost twelve years later, after an appeal to the High Court, his conviction was quashed, and a retrial ordered. However, the charges against him were dropped and Mallard was released. At the time, the Director of Public Prosecutions stated that Andrew Mallard remained the prime suspect and that if further evidence became available he could still be prosecuted.
In 2006 police conducted a review of the investigation and subsequently a cold case review. As a result, they uncovered sufficiently compelling evidence to charge convicted murderer Simon Rochford with the murder of Pamela Lawrence and to eliminate Andrew Mallard as a person of interest. After being publicly named as a suspect, Simon Rochford was found dead in his cell in Albany Prison, having committed suicide.
The Western Australian Commission on Crime and Corruption investigated whether there was misconduct by any public officer (police, prosecutors or Members of Parliament) associated with this case and made findings against two policemen and a senior prosecutor.
Mallard was convicted chiefly on two pieces of evidence. The first was a set of police notes of interviews with Mallard during which, the police claimed, he had confessed. These notes had not been signed by Mallard. The second was a video recording of the last twenty minutes of Mallard's eleven hours of interviews. The video shows Mallard speculating as to how the murderer might have killed Pamela Lawrence; police claimed that, although it was given in third-person, it was a confession.
Mallard had no history of violence; no murder weapon had been found. No blood was found on Mallard, despite the violence of the murder and the crime scene being covered with it, nor was DNA evidence produced. He was convicted on the confessions purportedly given during unrecorded interviews and the partial video-recording of an interview. Despite this, Mallard's appeal to the Supreme Court of Western Australia in 1996 was dismissed.
In 1998, Mallard's family enlisted the help of investigative journalist Colleen Egan, who in turn managed to get John Quigley MLA and Malcolm McCusker QC involved. All were appalled at the manner in which Mallard's trial had been conducted and eventually came to be convinced that he was innocent. Based on fresh evidence uncovered by this team, including a raft of police reports that, against standard practice, had never been passed to the defence team, the case was returned to the Court of Criminal Appeal in June 2003. Despite the fresh evidence and an uncontested claim that the DPP had deliberately concealed evidence from the defence, the Court of Criminal Appeal again dismissed the appeal.
In October 2004, Mallard's legal team was granted special leave to appeal to the High Court of Australia and on 6 and 7 September 2005, Mallard's appeal was heard in the High Court and the Justices subsequently judged unanimously that his conviction be quashed and a re-trial be ordered. During the hearing, Justice Michael Kirby was reported to have said that on one of the pieces of evidence alone—a forensic report, not disclosed to the defence, showing that Mallard's theory about the weapon used in the murder could not have been true—a re-trial should have been ordered.
The DPP did not immediately drop charges against Mallard but did so six months later immediately before a directions hearing was due. After almost twelve years in prison, Mallard was released on 20 February 2006. However, in announcing that the trial would not proceed the DPP stated:
"Finally, I note for the record and for the future that this decision is made on evidence presently available to the prosecution. The discharge of Mr Andrew Mallard on this charge does not alter the fact that he remains the prime suspect for this murder. Should any credible evidence present in the future which again gives the state reasonable prospects of obtaining a conviction again, the state would again prosecute him."
A documentary titled Saving Andrew Mallard was directed by Michael Muntz and produced by Artemis International, focussing on Mallard's family, its struggle to have him freed, the deception undertaken by the original police investigation team and the evidence uncovered that eventually led to Mallard's freedom. It was first aired on Australian Broadcasting Corporation (ABC) Television on 4 May 2006. It was short-listed for a Walkley Award, and Michael Muntz won the Outstanding Achievement in Directing Award in the WA Screen Awards.
The documentary's epilogue noted that the DPP still considered Mallard a prime suspect in its investigation at that time.
Following the discontinuation of the prosecution by the DPP, the Commissioner of Police instituted a review of the investigation to establish whether there were sufficient grounds for a "cold case" review. The review quickly located a record of a palm print which matched that of Simon Rochford, who had confessed to murdering his girlfriend, Brigitta Dickens, on 15 July 1994, seven weeks after Mrs Lawrence was killed. The print had been found on the top of a display case in Lawrence's shop, which was significant, as it had been the practice of the shop staff to wipe the top of that case after each customer left.
On this basis the review became a cold case review. The weapon used by Rochford to kill Dickens was a steel collar of the type used by weight lifters to secure weights to a bar. Rochford had attached the collar to a broom handle and used it to club Dickens to death. The actual collar could not be located in 2006 but its dimensions were known and a photograph was available. The shape and dimensions of the collar were consistent with the form of the wounds in Lawrence's skull.
The photograph of the collar indicated that it was painted blue and a rucksack belonging to Rochford was found to contain blue paint flakes which were identical in chemical composition to those removed from Mrs Lawrence's wounds.
Rochford's appearance, in particular his beard, was more consistent with the original accounts of eyewitnesses than was Mallard's.
On 12 May 2006, five police officers were stood down by the West Australian Police Commissioner in relation to the original investigation into the murder.
At about 7:45 am AWST on 19 May 2006, the body of Simon Rochford was discovered in his cell at Albany Maximum Security Prison by prison officers, just hours after he had been named as "a person of significant interest" in the Pamela Lawrence investigation.
On 11 October 2006, the Police Commissioner announced that the cold case review was complete, that Andrew Mallard was no longer a person of interest in relation to the case; that there was sufficient evidence to implicate Simon Rochford and that, if he had still been living, the police would have prepared a Brief of Evidence against him for the WA Director of Public Prosecutions.
The Police Commissioner apologised to Mallard for any part the police had played in his conviction. The Premier indicated that the government would be considering compensation, though the Attorney General stated that no decision could be made until the Commission on Crime and Corruption had completed its investigation. However, on 22 November 2006, the Adelaide Advertiser carried an AAP story stating that Andrew Mallard had received a AUD$200,000 ex gratia payment as partial compensation.
The Commission on Crime and Corruption (CCC) announced that it was studying the report of the cold case review and would be holding public hearings in 2007. In the meantime it had asked the police to not release the full report, either to the public or within the police service, and in particular, to ensure that police involved in the original investigation had no access to it. The CCC hearings into whether police and/or prosecutors behaved unethically or illegally in the Andrew Mallard case began on 31 July 2007.
On 7 October 2008 the CCC announced its recommendations that disciplinary action be taken against two assistant police commissioners and the deputy director of public prosecution. The two police officers subsequently resigned, thereby removing any chance of disciplinary proceedings going ahead.
In May 2009, Andrew Mallard was offered a payment of $3.25 million as settlement though the Premier of the state, Colin Barnett, said that were Mallard to take civil action against those he held responsible for his wrongful conviction, the government would support any servant of the state in that event.