[Boogieman]

The investigation isn’t over yet, so no there isn’t something like an “official timeline”. The best we’ve got, I think, is the police radio logs, since they are a record of what was going on as it happened, and they are publicly available.

[Uncle Chip]

and there is always wiki:

http://en.wikipedia.org/wiki/Sandy_Hook_Elementary_School_shooting

[Resettozero]

The investigation isn’t over yet, so no there isn’t something like an “official timeline”. The best we’ve got, I think, is the police radio logs, since they are a record of what was going on as it happened, and they are publicly available.

The investigators gave information for the first day or two, but after the sadness of the situation became the news lead (the dead heroes, the funerals), the official investigators and the media have made a poor effort at informing the nation about further findings and making clarifications. Again, no one is on trial here; no legal need to keep investigations a secret.