(RALEIGH) -- The state senator who is leading the investigation into the Department of Transportation said two days of testimony have not done much to clarify a dispute over the content of letters sent legislators. Sen. Tom Apodaca led the hearings at which Perdue aide Pryor Gibson and DOT chief operating officer Jim Trogdon relayed their version of events.

Apodaca said all options are still on the table as they continue their investigation. "We can continue the inquiry.  We could see if we think there is enough to make any referrals to any other committees, government entities or whatever, but we're still looking," said Apodaca.

Trogdon said in testimony before the committee that he did not approve changes to letters that appeared to reverse the DOT's position on two toll roads. The letters carried Trogdon's digital signature.

A staffer for Governor Bev Perdue says letters that were altered and sent out under Trogdon's signature were just a misunderstanding. Pryor Gibson is accused of using pressure from the Governor's office to have the letters altered without the Trogdon's permission. Gibson said he thought the changes to the letters were legitimate until he heard from Trogdon himself.

The Senate investigative committee will meet again on Tuesday.