HAVERHILL, N.H. – Three people testified before a grand jury Monday in the case involving two Vermont teens charged with killing two Dartmouth College professors.

The investigative panel, meeting in secret in Grafton County to decide whether to issue any indictments, will meet again Tuesday.

Reportedly the three witnesses who testified Monday were two friends of the teens and one of the friends’ father.

The Chelsea, Vt., teens are charged with first-degree murder in the stabbing deaths of Half and Suzanne Zantop in their isolated off-campus home in Hanover on Jan. 27.

Robert Tulloch, 17, is being held in the Grafton County Jail while James Parker, 16, is being held in a juvenile center in Concord.

The boys’ parents did not testify Monday. Prosecutors said the parents were interviewed by investigators during the weekend to avoid the grand jury.