New London Superior Court Judge Kevin P. McMahon declared a mistrial this morning in the robbery trial of Sharnon I. Lee after two members of the jury admitted they went online over the weekend to investigate the case.

Lee, 37, of Norwalk is accused of following a patron from the Mohegan Sun casino to his car in August 2010, holding a knife to the back of his head and robbing him of $3,800 and a cell phone. He is charged with first-degree robbery and second-degree larceny, and the six-member jury had the option of finding him guilty on the lesser charges of second-degree robbery or third-degree robbery.

The jury began deliberating late Thursday. On Friday, the panel sent the judge a note asking him about the definitions of robbery and larceny. McMahon reinstructed the jurors and told them to continue deliberating. He dismissed them early, at about 3:15 p.m., because of a personal issue.

During the trial, the judge repeatedly instructed the jurors to refrain from conducting any independent investigation and to decide the case based only on the evidence they heard in the courtroom.

Defense attorney Steven Delio said there seemed to be some confusion on Friday, so he asked the judge today to inquire whether the jurors had conducted any independent investigation. Two of them admitted they had gone to the Connecticut Judicial Branch website and had looked up the definitions of larceny and robbery. As a result of their admissions, McMahon declared a mistrial due to juror misconduct.

Prosecutor Lawrence J. Tytla said the case would be tried again, but could not say when. Lee, his mother and his uncle left the courthouse disappointed that the case had not been resolved.