United Kingdom, June 14 -- Larry Birkhead has "always tried to protect" his daughter since the death of Anna Nicole Smith.

The 52-year-old photographer is father to Dannielynn, 18, with the legendary supermodel - who died of a of a drugs overdose at the age of 39 just six months after she gave birth in 2007 - and admitted it was "hard" to know just who to trust when he was bringing their daughter up alone.

He told E! News: "It's hard. When she was younger and had friends over, or went out, it was tough figuring out who was genuine.

"I've always tried to protect her not just from media and paparazzi, but even people we let into our circle.

"Some had great intentions, but others didn't.

"Some would say, 'I want to hang out with you bec...