A state lawmaker investigating a scandal into the Registry of Motor Vehicles says he believes the governor’s office is deliberately withholding information related to his investigation.

“In a number of instances we have become aware of documents and have stated them publicly where they haven’t been provided to us,” House Transportation Committee co-chair Rep. William Straus told Jim Braude on Greater Boston Thursday.

“More and more each day, I have to come to a conclusion that someone in the administration prefers not to share information,” Straus added, reiterating claims he first made on Monday.

Massachusetts Department of Transportation spokesperson Jacque Goddard said in a statement Thursday to WGBH News that "MassDOT conducted a thorough search which resulted in the production of nearly one million responsive pages" based on the committee's record requests.

"MassDOT has not been contacted by the committee regarding this production and again has learned of this question through the media. MassDOT will continue to work with the committee on any requests to assist their investigation," Goddard said.

Straus' investigation is seeking to determine what state officials knew — and when — about the RMV’s failure to process alerts from other states about Massachusetts drivers. This failure created a massive backlog, which allowed thousands of unsafe drivers — including one that killed seven motorcyclists in New Hampshire earlier this year — to remain on the road.

A separate investigation conducted by an outside firm retained by the governor’s office determined that the state had a “longstanding policy of not prioritizing the processing of out-of-state notifications.”

Straus contended on Thursday that there were still documents relevant to the investigation that were not provided to his committee by the administration. He said his investigation has had to rely on "several" outside sources who have contacted his committee.

When asked which documents he would like to receive from the administration, Straus said he wants the full transcripts of the interviews conducted by the auditing firm, Grant Thornton, retained by the governor’s office.

Straus also requested documents that he alleges were handed out at meetings about the RMV issues by state officials.

“They should release them tomorrow,” Straus said.

Straus clashed with Baker administration officials earlier this week over two emails he received from independent sources that were not provided to him by the governor's office.

As WGBH News reported, the emails contained Baker's Deputy Chief of Customer Service and Constituent Affairs Mindy d’Arbeloff's replies to a discussion of how software tracks out-of-state violations.

"This is not an email conversation. We will gather a meeting." d'Arbeloff replied to an email with the subject "Scanning and OOS Processing," dated July 16, 2019, weeks after news of the scandal broke.

MassDOT spokesperson Jacque Goddard responded to Straus's claim on Monday that "MassDOT has not been contacted by the committee regarding this production and again has learned of this question through the media. MassDOT will continue to work with the committee on any requests to assist their investigation."

When asked if he had evidence suggesting Gov. Charlie Baker and Transportation Secretary Stephanie Pollack knew of the issue in advance, Strauss said he does not. Baker has said that he knew nothing about the issue until then RMV Registrar Erin Devaney resigned in June.