TORONTO -- Ontario's opposition parties accused the Liberal government of protecting its own Thursday as a legislative committee wrapped up its investigation of the $1.1-billion gas plants scandal without calling two key witnesses.

At the same time, the public learned that police served a search warrant last month at a government office seeking deleted emails about the Liberals' decision to cancel gas plants in Oakville and Mississauga prior to the 2011 election.

The Liberals used the majority they won in the June 12 election to force the legislative committee that was holding hearings into the gas plants to wrap up its work Thursday and write its report.

The Progressive Conservatives and New Democrats, who plan to write dissenting reports, had wanted the committee to hear from two more witnesses: former Dalton McGuinty senior aide Laura Miller and her computer-tech boyfriend Peter Faist, who had been under contract to the Liberals until earlier this year.

"Those are two people that could shed a lot of light as to what actually happened," said PC energy critic John Yakabuski. "There are a lot of questions still to be answered, but the Liberals don't want to hear those answers come out."

The Liberals' decision to shut down the gas plant hearings show Premier Kathleen Wynne is only paying lip service to her claims of running an open and transparent govermment, said NDP Leader Andrea Horwath.

"Throughout this session, Liberals have been trying to whitewash the gas plant scandal," she said. "But Laura Miller and Peter Faist, two Liberal insiders who were, frankly, at the centre of this scandal are still being protected."

Deputy Premier Deb Matthews said the committee had heard months of testimony from dozens of witnesses and now it was time to hear its recommendations.

"There's a time for good things to come to an end," said Matthews. "It's time for that to wrap up."

Meanwhile, Wynne's office confirmed Thursday that the OPP served a search warrant in November on IT staff at a provincial cyber security office in Toronto.

The warrant asked for the electronic mailbox and its backup tapes for Miller and for McGuinty's former chief of staff, David Livingston, between May 1, 2012 and Feb. 11, 2013 -- the day Kathleen Wynne was officially sworn in as premier.

In a previous court document, police alleged that Miller gave Faist access to files in the premier's office that were then wiped clean.

Police had said Livingston was under investigation for breach of trust, but he has not been charged, and through his lawyer has denied breaking any laws.

Wynne's office said IT staff at the cyber security branch co-operated with the OPP, and pointed out that the court order was not directed at any ministers, MPPs or current political staff.

"The Liberal government is certainly protecting themselves because they do not want the whole story to be revealed," said Yakabuski. "We're just hopeful that the OPP's investigation will bring out all the facts."

It was the Liberal's initial refusal to hand over gas plant documents to an opposition-dominated legislative committee that led to a rare contempt of Parliament charge and forced McGuinty to resign as premier under a cloud of scandal in Oct. 2012.

Wynne had apologized repeatedly for the gas plants scndal, which the opposition parties had called "an expensive Liberal seat saver campaign" after the auditor general warned it could cost $1.1 billion to compensate the original developers and build the two gas plants in new locations.

The scandal did not hurt the Liberals in this year's election, when they were returned with a majority after two and a half years in a minority government.