The only person out of the 3 with the tattoo who could have killed the private detective woman is McAllister.

Bertram is 6'3, Smith is 6'2. 

When the woman opens the door, she doesn't look up. Their eyes are on the same level.
She is not a giant like those 2 men, in fact she is about Cho's height.

The only person who is not above 6 feet is the sheriff.

I don't know if he is Red John or not, but out of the three it can only be him who killed the woman.