Using the bad guy's finger, who is dead, to access the fingerprint protected smartphone.
Opening the phone. As they need to access again the phone, a solution has to be found.
So now, I have his password. Where can I hide this?
Inside the lipstick. Good idea, and funny.
... and accessing the message.
BTW, it was easier to re-enroll her finger in place of the guy's finger.
But less interesting for the movie.