It's round two of the State Senate investigation into Sound Transit.

Last week, the Senate Law & Justice Committee held its first investigatory hearing, looking into whether Sound Transit misled the public and the legislature about the cost and impact of the tax package known as Sound Transit 3.

"I've gotten emails from folks who voted for ST3 and they feel absolutely side-swiped by the lack of information they received about how much they're going to be paying," said Senator Steve O'Ban, R-University Place.

During Thursday's investigative hearing, lawmakers focused on a few other issues.

First, they want to know if Sound Transit violated campaign laws and illegally meddled in the ST3 ballot initiative. They're also looking at whether the agency intentionally used an outdated method to calculate the car-tab fees that left so many drivers feeling sticker shock.

Sound Transit strongly denies the allegations, saying it followed all campaign laws and was completely transparent about all aspects of ST3. You can read Sound Transit's full response to the allegations here.

"The issues some of the Senators raised today have been reviewed thoroughly, and there have been findings by investigating entities such as the attorney general that were was no wrongdoing by Sound Transit," said Sound Transit spokesperson Geoff Patrick, who was called to testify at both investigatory hearings.

Sound Transit says this ST3 Revenue Development Timeline shows the efforts the agency took to educate the public about the cost and impact of ST3, long before voters weighed in.

Voters approved the $54 billion ST3 tax package last fall. Sound Transit says the ST3 tax increases will pay to expand mass transit in King, Pierce, and Snohomish counties with a range of light rail, commuter rail, and bus connections.

On Thursday, lawmakers spent more than three hours listening to testimony and asking questions of Sound Transit staff members. The executive director of the Transportation Choices Coalition and other transit advocates were also called to testified.

Leading up to the investigatory hearing, Senate Law & Justice Committee members and staff reviewed over 7,000 pages of documents provided by Sound Transit in response to public disclosure requests.

Many of lawmakers' questions on Thursday focused on the relationship between Sound Transit and transit advocacy organizations like the Transportation Choices Coalition.

Sen. O'Ban also criticized Sound Transit's release of 173,000 personal email addresses of ORCA cardholders that were given to the group in charge of the campaign for ST3.

Sound Transit has acknowledged the release of those email addresses, but says it was not done intentionally. Instead, the agency says the emails were mistakenly released in response to a public disclosure request. The agency says the Sound Transit staffer who filled that request did not realize that ORCA cardholder email addresses were exempt from disclosure.

"To your knowledge, was anyone disciplined by Sound Transit in any way for this improper disclosure of Sound Transit's personal customer emails?" Senator O'Ban asked Sound Transit staffers at Thursday's hearing.

In response, Sound Transit said no employee was disciplined for the error, but they do regret that it happened.

"We certainly didn't want to do something that was wrong," said Craig Davidson, Sound Transit's Executive Director of Communications and External Affairs. "Every employee involved carried a heavy burden and was not happy with how any of these events unfolded."

Much like last week's hearing, Democratic Senators on the committee did not seem to agree with O'Ban's line of questioning. Sen. Jamie Pedersen, D-Seattle, and Sen. David Frockt, D-Seattle, both expressed support for Sound Transit when they spoke during the hearing.

"I really struggle to understand what the connection is to the Senate Law & Justice Committee. I think it's appropriate for the transportation committee to do oversight of Sound Transit," said Pedersen. "I guess the thread they're trying to hang this on is that it's fraudulent, but we certainly didn't hear any testimony today that would suggest there was knowing deception."

But the chair of the Law & Justice Committee disagrees.

"I think there are a lot of concerns," said Senator Mike Padden, R-Spokane Valley.

So what comes next in this Senate investigation?

"I think the committee will make recommendations to both the House and Senate transportation committees for greater oversight of Sound Transit, and I certainly hope Sound Transit will make some reform themselves because obviously people feel misled," said Padden.

Lawmakers could opt to address the investigation's findings with new legislation aimed at holding Sound Transit accountable. The committee could also choose to hand its findings over to the state attorney general or a county prosecutor for further review.

Senator O'Ban said he plans to re-introduce his proposal that would allow voters to directly elect Sound Transit Board members. He believes doing so would provide more accountability. Sound Transit board members are currently appointed rather than elected.