When talking to Detective Lexi in Golden Gate Park, pick these dialog choices:
1. Don't rush on my account. Just a man's life on the line.
2. Can you just escort us into the apartment yourself?
3. You know I can handle myself, Lexi. You've been there.
After that, interact with the water pump to turn off the water. Go left. Ask the Park ROM for some water. It should run to the right and into Lexi, causing her to drop her ID. Interact with the ID.