HARRISBURG -- Gov. Ed Rendell says public money shouldn't be spent on a private eye to investigate a lobbyist's failure to register before pushing for a tax credit for film companies this summer.

Sen. Jeffrey Piccola, R-Dauphin, said the Senate's State Government Committee, which he chairs, plans to hire an investigator to examine the actions of lobbyist Leslie M. McCombs and Lionsgate, a Santa Monica, Calif., film company for which she lobbied in June and July.

"We need to find out who did what for whom and when," Mr. Piccola said yesterday. "We may have to plug some loopholes or inadequacies in the lobbying law. We want to be able to tell the public we have a law that works."

He plans to contract with a Pennsylvania firm that employs ex-state troopers and ex-FBI agents. He'll reveal the name by the end of the week when he signs the contract. The cost, which he didn't think would exceed $10,000, will come from a Senate Republican leadership account.

Mr. Rendell, a Democrat, said yesterday that it's fine if Mr. Piccola's panel holds hearings aimed at improving the lobbying law enacted last year, but said he saw no reason to spend state money on an outside firm.

"I don't think we need a private detective" to look into an oversight by Ms. McCombs, he said. "I think Sen. Piccola and the committee can just talk to people involved."

Mr. Piccola said, "It's a complex set of facts and we don't have the time or the expertise to look at it with our present staff."

Ms. McCombs, a former Fox TV reporter in Pittsburgh, is a friend and fund-raiser for the governor. She was already registered as a lobbyist for the University of Pittsburgh Medical Center, but sent out e-mails in June supporting a proposed $75 million tax credit for companies that shoot movies in Pennsylvania.

She didn't register as a lobbyist for Lionsgate until Sept. 4, after she was asked about her lobbying efforts by a Harrisburg online news service called Capitolwire.

"I've amended my filings with the commonwealth and am in full compliance with the [2006 lobbying] law," she said in an e-mail yesterday to the Pittsburgh Post-Gazette.

But Mr. Piccola said he wanted answers about discrepancies in dates on forms filed with the state Department of State by Ms. McCombs and Lionsgate. The Lionsgate form says she began work May 1 and ended work June 30. Her form says she started June 11 and doesn't list an end date.

The Legislature approved the $75 million tax credit in July. Backers said it will give a sharp boost to Pennsylvania's economy as more films are made here. Mr. Rendell said Lionsgate has already helped Pittsburgh by filming the "Kill Point" TV series there.

The current law contains penalties if a lobbyist's failure to register is "negligent" or "intentional." A lobbyist can be fined up to $50 a day for each day he or she is late in registering.