The cinematic movie reveals that Travis meets with Blake Dexter to make the exchange with Victoria.
Then, 47 has to infiltrate residential building to eliminate Layla in order to go after Dexter and Victoria.
In Blackwater Park we can acquire two Hitman Absolution Evidence collectibles, and the following guide describes where we can find them.
Note: Challenges cannot be completed on EASY
Hit Him Where It Hurts
Blackwater Park. A building under siege. Dexter will be expecting my arrival. I took his son. If he is mad enough to take on the Agency, would he also sacrifice Victoria to get back at me? I need to be careful. But one way or the other, this is where it ends.
Evidence 1 – Blackwater Park
We start the level outside, where we can walk freely. However, the building is off limits and so is the nearby park.
There are many ways to infiltrate the building, but no matter what, we have to reach the other side of the building, near the garage entrance.
The first Hitman Absolution Evidence is inside a small security office, but there are two guards around, and if we use a guard disguise it may be difficult to acquire. A quick way to get it is to acquire the custodian disguise from the guy that is working in the garden.
Two guards are patrolling nearby, but if we manage to distract them and get rid of them, we should easily obtain the disguise (or we can turn off the water pump near the garage to make one of the custodians come out from the building).
Once we have it, we go inside the security room and we grab the videotape containing the Evidence from the recorder under the TV monitors.
A better disguise is the one we can get from the plumber that is getting out of the building through the doors that are above the garage entrance (left side as were looking at the garage).
Evidence 2 – The Penthouse
After we find a way to use the retinal scanner we can access the elevator. On the top floor, the enemies attack the elevator.
Then, we need to escape through the maintenance hatch and we use the ledge to get inside the penthouse. If we turn left and then left again where the stairs are, we can access an area where many weapons are displayed. If we go further in this area, we reach a large hall where a whale skeleton is hanging by the ceiling. While facing the skeleton, we turn left to see a couch.
On the couch we can find the second Evidence collectible in Blackwater Park level.
Probably the easiest way to acquire the collectable is to get a bodyguard uniform and then patiently get rid of the guards in the area, one by one.
We eliminate Layla, and after we answer the phone in the panic room we can begin the next mission in line, Countdown.