A Maryland judge yesterday dismissed four counts of extortion against former state senator Larry Young, ruling that prosecutors had failed to make a strong enough case for a jury to consider whether the once powerful lawmaker was guilty of the charges.

While the decision was a setback to State Prosecutor Stephen Montanarelli, four bribery charges and a charge of filing a false state income tax return are still pending against Young. His case could go to the jury as early as today.

Once an influential Democrat from Baltimore, Young was indicted in December for allegedly extorting bribes to help a Prince George's County health-care company obtain a lucrative state contract to treat Medicaid patients. Central to the case was the testimony of a radiologist who owned the company, Christian Chinwuba, who testified that he paid Young cash. But in his testimony he said he never felt the payments were bribes and that Young had not promised to do anything for him.

"The court is just convinced after listening to Dr. Chinwuba's testimony . . . that it's impossible for a jury to conclude there was extortion," Anne Arundel County Circuit Court Judge Joseph P. Manck said in dismissing the charges.

Assistant State Prosecutor A. Thomas Krehely Jr. acknowledged in court that Chinwuba was not "a model of consistency." Still, he argued that prosecutors had made a strong case against Young.

"A public official doesn't go to a private person and ask for gifts and ask for money unless they have the intent to use their office" to help the person, he told the judge.

The former senator's attorney, Gregg Bernstein, however, apparently is banking on the jury disagreeing. He opted not to offer any defense after prosecutors concluded their case yesterday.

While Chinwuba testified to making cash payments and providing Young with two computers, "there is absolutely no evidence that any of those things were paid or given in order to influence him in his duties," Bernstein said during arguments to Manck without the jury present.

In his opening remarks to the jury last week, Bernstein said that Chinwuba began cooperating with prosecutors only after Maryland insurance regulators launched an investigation of his company, PrimeHealth Corp. of Lanham. Regulators have since put the company into receivership, saying they found mismanagement and $650,000 in cash missing from the business.

Bernstein said he planned to show that Chinwuba had misspent the money himself. But now, he will not be able to follow through with that, given that he has chosen not to put on any witnesses--including Young--to counter testimony that the doctor paid the former senator cash during a series of meetings after business hours at his Lanham office in 1995 and 1996.

Young was chairman of the Senate's subcommittee on health and chairman of the black legislative caucus until January 1998. After reports in the Baltimore Sun about his possible conflicts of interest, the General Assembly's Joint Committee on Legislative Ethics investigated Young. The Senate voted to expel him, making Young the first state senator from Maryland ever forced from office.

CAPTION: Ex-senator Larry Young is surrounded by reporters during a break in his trial.