Who realized there was no government fingerprint database print for Luke?

Jen....

“Fingerprints,” Jen said. When Luke gave her a blank look, she explained. “My brother Brawn went through this phase where he wanted to be a detective—not that he ever would have been smart enough for it—and I remembered he still has a fingerprinting kit. So I dusted for your fingerprints on things you touched, just like on TV. I got a really good print off the wall. Then I scanned that into the computer, linked into the national file of fingerprints and, voilà, I discovered your fingerprints don’t exist, so neither do you. Officially.”