In yet another blow to the Crimson Sports Grille, investigators for the Cambridge License Commission (CLC) will testify that they found a 20-year-old Boston University student drinking illegally inside the popular Harvard night spot on March 23, CLC files show.

The alleged violation comes on the heels of a Dec. 15 sting by the Massachusetts Alcoholic Beverages Control Commission (ABCC) that found six minors drinking at the bar. As a result of the violation, the ABCC recently decided to suspend the Grille's license from May 22 to June 8 without the possibility of a fine replacing the suspension.

CLC investigators will reveal the results of the latest sting on May 8.

According to recently released files, investigators Andrea Boyer and William C. Barnes visited the Grille on the evening of March 23, after finding no violations at 10 other Square establishments that same evening.

Boyer informed the Grille's bouncer that they would enter the bar and ask customers for identification. They then proceeded to a table, where they carded eight patrons.

Seven produced valid identifications, the investigators' report said, but one woman with a Midori sour said she had no ID. When the investigators informed her they were conducting a sting, the woman began to cry. She told them she was 20 and that her friend who had already left the bar was in possession of the fake driver's license she had used to enter.

In response to this most recent alleged violation, the CLC could shorten the Grille's operating hours or suspend or revoke its license, said CLC Executive Director Richard V. Scali.

"We consider all past history in regards to progressive discipline," Scali said. "We're at a crucial point in our history with Mr. [Paul C.] McCarthy," the Grille's owner.

Despite earlier speculation that McCarthy might sell the establishment, Scali said he has not received any more inquiries from potential buyers over the past week.

The CLC will announce any possible punitive measures against the Grille on May 24.

If CLC does decide to suspend the Grille's license, its suspension will take effect after the ABCC's concludes, Scali said.

The Grille's lawyer, James J. Rafferty, declined to comment for this story.

-Staff writer Daniel K. Rosenheck can be reached at rosenhec@fas.harvard.edu.