Provincial police say computer experts still cannot determine exactly when computer hard drives in the Ontario
premier's office were accessed with a special password that could have allowed files to be erased.

The OPP is  investigating the deletion of emails related to the Liberals' decisions to cancel two gas plants prior to the 2011 election at a cost of $1.1 billion dollars.

The emails are alleged to have been deleted during last spring's transition period when outgoing premier Dalton McGuinty was getting ready to leave office and Kathleen Wynne was set to take over.

Last month, provincial police seized 24 computer hard drives that had been removed from the premier's office as part of their investigation.

Det. Const. Andre Duval told the justice committee Thursday that the government's Cyber Security Branch had only been able to determine when four of the 24 computers had been accessed with a special password.

The dates are important because the Opposition says the date range in a requested search warrant goes past  Wynne's swearing in as premier but Wynne denies any files were accessed after she took over from Dalton McGuinty.

Duval's testimony Thursday largely stuck to information that is already public, but he did say that neither Wynne, nor anyone in her office, are under investigation.

Duval testified the police investigation so far has focused only on McGuinty's former chief of staff, David Livingston.

A document police used to obtain search warrants in the case alleges Livingston gave an outside tech expert Peter Faist access to computers in the premier’s office. Faist has been described as the boyfriend of Laura Miller, Livingston's deputy during his time in McGuinty's office.

A statement from Miller's lawyer said she was willing to cooperate with the OPP, but Duval testified Thursday that she declined requests from OPP investigators for a statement.

Duval also testified it could be months before all the computer hard drives are accessed.

Wynne was not in question period on Thursday to answer any criticisms related to Duval's testimony but later told the media the OPP investigation did not involve her office.

"I know the detective who was there made it clear that my office is not under investigation, that the investigation centred on the former premier's office, and I really believe we need to let that investigation unfold," said Wynne.

Faist to testify

Duval testified that Livingston, McGuinty's former deputy chief of staff Laura Miller, her boyfriend -- outside tech expert Peter Faist -- and former Liberal staffer Wendy Wai have all refused to co-operate with the police investigation.

Miller's lawyer has said she is willing to cooperate with investigators and Faist will testify before the committee next Thursday.

Faist had a government contract that ended when Wynne took office on Feb. 11, 2013, though his contact with the party ended only last Sunday.

Duval was asked during his testimony if the OPP had any evidence that computer expert returned to the premier's office after Feb. 7 or accessed the hard drives in any way.

"Not as of today, no. We're hoping that the forensic examination will reveal that information," he said.

With files from CBC's Genevieve Tomney, the Canadian Press