A grand jury has ended a seven-month investigation of allegations of bribery and favoritism in the Montgomery County Department of Liquor Control without bringing any criminal charges, county State's Attorney's Andrew Sonner said yesterday.

"We have concluded that any further effort by the police, this office or the grand jury will not be productive," said Sonner. He stressed that the probe had not involved elected officials, against whom he said allegations of criminal behavior were never made.

The 23-member jury, meeting twice monthly, began its investigation last summer after charges of bribery, favoritism and questionable purchasing practices at the department, which holds a $70-million-a-year monopoly on liquor sales in the county, became a volatile issue.

County Executive Charles Gilchrist, whose administration has been plagued by the repeated claims of liquor-related misdeeds, expressed satisfaction with the jury's report. "Its conclusions clear the air," he said yesterday. "I concur with the state's attorney that 'now it's time for us to get on to other matters.'"

The jury's investigation proceeded alongside three other inquiries by the County Council, personnel board and the auditing firm Touche Ross & Company. Touche Ross's $125,000-study, made public in January, found evidence of mismanagement but not of favoritism. The council's and personnel board's studies still are pending.

Gilchrist is scheduled to meet with personnel board officials next week. They are expected to discuss allegations that Gilchrist and his aides improperly offered county jobs to consultant Leonard Colodny, who later was hired by Gilchrist to conduct a liquor study.

The liquor affair began last summer following newspaper reports documenting a long-standing revolving door pattern between the liquor department and certain liquor firms that sell to it. The articles also raised questions about the profitability of liquor sales in Montgomery, the only county in the country to monopolize alcohol sales this way.

The articles noted that Charles Buscher, former head of the department and one of Gilchrist's liquor advisers, had once pleaded quilty in West Virginia to seven of 23 counts of illegally inducing state officials to buy from the New York-based distilling firm Schenley industries.

Amidst increasing interest in the press and public forums, county police sought to reopen investigations of the department's former deputy head, Ken Dragon, who allegedly had attended a World Series baseball game in 1977 as the guest of Sohenley.

The just-concluded grand jury probe appears to have focused on Dragon and other alleged cases of liquor firms seeking favor with county officials through bribes and gifts. However, the long investigation, which involved five full-time investigators, turned up no information that would warrant indictments, according to Sonner.