Anna Nicole Smith's ex-boyfriend LARRY BIRKHEAD is laughing off reports he's under investigation as a deadbeat dad - because he knows he's doing his best as a single father. The photographer took charge of Smith's baby girl Dannielynn in April (07) after a lengthy paternity battle. He has since won custody of the child, pending a new legal challenge from the baby's maternal grandmother Virgie Arthur. And, in a bid to strengthen her case, Arthur - Anna Nicole's estranged mother - has called in a team of private investigators to keep an eye on Birkhead and report back if he slips up as a dad. But Dannielynn's biological father isn't worried: "They can follow me to (family restaurant chain) Chuck E. Cheese's and the toy store and the diaper store or wherever." Birkhead helped his cause as a single father by appearing on Fox News and CNN earlier this week (beg11Jun07) with his baby girl in his arms. Both news anchors Larry King and Greta Van Susteren commented how natural he looked as a father and how much he seemed to love his child.