On Monday morning, the jury heard detailed and technical testimony about cellphone data, which the prosecution is using to try to establish John O'Keefe’s location before he was found unconscious in the snow outside the Canton home.

The dense snow and blizzard-like conditions outside the Massachusetts home are gone. But the mystery of who may have killed Boston Police Officer John O’Keefe on a frigid night in Canton lingers as jurors visited the house near where his body was found.