A former president of the authority, Tim Lizura, also acknowledged that many last-minute changes to the law were made by Mr. Sheehan. The Times found that those alterations were done without any public disclosure.

Companies had been awarded $4.9 billion under the 2013 legislation by moving to New Jersey or remaining in the state and creating and retaining jobs.

The hearing was the second held in recent months by the task force, which in April referred evidence to federal prosecutors for possible criminal charges. It is not immediately known whether the evidence might lead to charges or what might result from Thursday’s testimony.

But a member of the task force said companies could be held criminally liable.

“There is real criminal exposure for companies that lie to the E.D.A.,” said Pablo Quiñones, a special counsel on the task force.

For several hours, another special counsel, Jim Walden, displayed some of the specific edits of the bill on a large screen. Some changes, he noted, were intended to allow specific companies, such as Subaru of America, to claim hundreds of millions of dollars in additional tax breaks.

Several companies had business ties with Mr. Sheehan’s firm, Parker McCay, Mr. Walden said.

Mr. Sheehan did not register with the state as a lobbyist for the Economic Opportunity Act, and his firm told The Times that its work on the legislation did not amount to lobbying.

“Parker McCay was asked by policymakers, including those in the Legislature, to review this legislation and offer input and suggestions on ways it could be strengthened to help Camden and other localities in South Jersey, which have historically lost out to North Jersey in receiving economic benefits from the state,” the company said in a statement on Thursday.