"Active investigation" means a the pre-arrest phase of investigation. E.g., they send a cop by a suspected trap house but don't want to tip off the residents that they are under suspicion. Otherwise, a criminal organization would just request all the body cam footage each week to make sure they aren't being investigated (or change their tactics in response to the police movements).

If there's an actual arrest and trial, the Supreme Court case of Brady v. Maryland (1963) requires that the state hand over any exculpatory evidence [1]. The state has to go out of its way to hand over evidence -- even if the defendant doesn't know it exists.

[1] "Exculpatory" = "might show that you are innocent." There's a long line of cases that define how broad that definition is.

* I am not your lawyer. Go get a criminal defense lawyer.