Britton Murder Grand Jury to Stay in Session The Middlesex Grand Jury, which normally sits from Jan. 1 to the end of June has been extended to the end of 1969 to continue receiving evidence in the murder of Jane Britton, 23- year -old Harvard graduate student, in her University rd.. Cambridge, apartment last Jan. 7. The extension was granted by Superior Court Judge David Rose at the request of Middlesex County Dist. Atty. John J. Droney. The move was made to preclude the confusion that would arise if evidence had to be presented to a second Grand Jury that starts its session on July 1.