VANCOUVER -- The former judge overseeing the Robert Pickton inquiry has received an extra four months to write his final report, but the extension will likely do little to allay critics who have demanded commissioner Wally Oppal spend more time hearing from witnesses about why police failed to catch the serial killer.

Oppal has been hearing evidence since last October about why police didn't catch Pickton in the late 1990s and early 2000s, but the inquiry has been sluggish as dozens of lawyers line up to cross-examine witnesses, some of whom have spent days and weeks at a time in the witness box.

The slow pace combined with a series of delays have made it increasingly unlikely Oppal would be able to finish his work before the previous deadline of June 30.

Oppal, who is scheduled to hear closing arguments next week, has asked the provincial government to have until Oct. 31 to write his final report, which will detail what police did wrong and what needs to change.

"He wants to take the appropriate amount of time to complete the report, to ensure that it has credibility, and I did agree to that," Attorney General Shirley Bond, who approved the extension, said in an interview Thursday.

"There needs to be a balance here. I am very concerned about ensuring that this report comes to a conclusion so that we can use the recommendations that will be provided to ensure that this kind of tragic circumstance doesn't happen again."

Last year, Oppal asked to be given until the end of 2012 to complete his work, but the province instead set his deadline for the end of June.

A number of families of Pickton's victims, their lawyers and the Opposition NDP have demanded Bond give Oppal more time, saying there are several witnesses that have yet to be heard that are important to understanding why police failed to catch Pickton as he murdered sex workers from Vancouver's troubled Downtown Eastside.

But Bond has repeatedly rejected those demands. She noted Oppal's latest request was only for time to write his report, not to conduct more hearings.

"The request that came to me was related to the writing of the report, the analysing of information, of literally months and months of work. He did not request an extension related to witness testimony," said Bond.

"The commissioner has assured me he has had the time required to understand the policing aspects that need to be changed."

Cameron Ward, a lawyer for the families, has argued there are a number of witnesses that still need to be heard and he asked Oppal to add more than a dozen to the hearings schedule.

The list included Ross Caldwell, a police informant who implicated Pickton years before his arrest; Lynn Ellingsen, who told Pickton's trial about seeing him murder a woman on his property; Bruce Chambers, a former Vancouver police chief; Beverly Hyacinthe, a civilian RCMP worker who knew the Pickton family; and police spokeswomen Anne Drennan and Catherine Galliford.

Ward also asked that Oppal hear from Pickton and his brother David.

Oppal rejected those witnesses and will write his report without their testimony.

The inquiry has been beset by delays and controversies since its inception.

Critics argued that Oppal, a former Liberal attorney general, was a poor choice to lead the commission.

A number of community and advocacy groups pulled out of the process last year when the province denied their requests for legal funding.

The inquiry was put on a three-week hiatus earlier this year when an independent lawyer appointed to represent aboriginal interests resigned, citing concerns that First Nations voices weren't being heard.

And the inquiry was rocked by sexual harassment allegations in April, when the National Post newspaper published anonymous allegations directed at an unnamed member of Oppal's staff. Oppal appointed an independent lawyer to look into those allegations.

The inquiry is looking into why the Vancouver police and the RCMP failed to catch Pickton while he was murdering impoverished sex workers, despite receiving tips implicating the former pig farmer as early as 1998. Oppal is also examining why prosecutors declined to put Pickton on trial after he was charged with attempted to murder a prostitute in 1997.

Pickton was arrested in February 2002 and eventually convicted of six counts of second-degree murder.

The remains or DNA of 33 women were found on his farm. He once told an undercover police officer that he killed a total of 49.

James Keller reports for The Canadian Press.