Democratic U.S. Rep. Martin Frost (search) is under investigation in Travis County for possibly using illegal corporate donations to help finance Texas legislative candidates.

State Sen. Robert Deuell, R-Greenville, filed a criminal complaint against Frost, of Dallas, last month. He alleged Frost was engaged in activities similar to those Travis County District Attorney Ronnie Earle has been investigating involving U.S. House Majority Leader Tom DeLay (search), R-Texas.

Frost campaign spokesman Jess Fassler said Frost has done nothing wrong.

The complaint alleged Frost raised corporate money in the 2000 election cycle and funneled it to state legislative candidates through a committee called the Lone Star Fund (search).

"Texas law is clear: Direct or indirect corporate or labor contributions to candidates is a felony offense," Deuell said in a letter to Earle. "I believe it is imperative that you investigate this matter."

In a Tuesday letter to Deuell, Earle, a Democrat, said his office's Public Integrity Unit (search) had opened an investigation into the new claims and thanked the senator.

"Such vigilance is the price of freedom from domination of our electoral processes by special interests," Earle wrote.

Fassler called the accusations "frivolous and malicious" complaints designed to help U.S. Rep. Pete Sessions (search), R-Texas, Frost's opponent in the November election.

Deuell said Internal Revenue Service (search) filings for the Lone Star Fund showed that between July 1 and Sept. 30, 2000, Frost raised $256,800, mostly from corporations and labor unions. Only $60,000 was raised from individuals who could legally donate to legislative candidates.

Fassler said Deuell's complaint erroneously relies on a filing report that did not include cash on hand from contributions made by individuals before the reporting period.

He said the fund maintained separate nonfederal accounts, one of which raised money eligible for use in state elections. He said that account did not accept corporate donations. It raised more than $400,000 in 2000 but distributed less than that to state candidates.

The other account, which accepted corporate money, did not contribute to Texas candidates, Fassler said. All fund raising complied with state and federal laws, he said.

Earle has been conducting a grand jury investigation into the possible illegal use of corporate money in the 2002 elections to help Republicans win legislative seats that gave the GOP control of the Texas House for the first time since Reconstruction (search).