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Input: After five days of scouring the life of Las Vegas gunman  Stephen Paddock  and chasing 1 000 leads  investigators confessed Friday they still don't know what drove  him  to mass murder  and they announced plans to put up billboards appealing for the public's help.
In their effort to find any hint of  his  motive  investigators were looking into whether  he  was with a prostitute days before the shooting  scrutinizing cruises  he  took and trying to make sense of a cryptic note with numbers jotted on it found in  his  hotel room  a federal official said.
So far  examinations of Paddock's politics  finances  any possible radicalization and  his  social behavior — typical investigative avenues that have helped uncover the motive in past shootings — have turned up little.
His arsenal also included tracer rounds that can improve a shooter's firing accuracy in the dark  a law enforcement official told AP. It wasn't clear whether  Paddock  fired any of the illuminated bullets during the high-rise massacre.
 Paddock  bought 1 000 rounds of the .308-caliber and .223-caliber tracer ammunition from a private buyer  he  met at a Phoenix gun show  a law enforcement official not authorized to comment on the investigation said on condition of anonymity.
Video shot of the pandemonium that erupted when  Paddock  started strafing the festival showed a muzzle flash from  his  room at the Mandalay Bay resort  but bullets weren't visible in the night sky.
Investigators are looking into  Paddock 's mental health and any medications  he  was on  McMahill said.
 His  girlfriend  Danley  told FBI agents Wednesday that she had not noticed any changes in  his  mental state or indications  he  could become violent  the federal official said.
 Paddock  sent Danley on a trip to her native Philippines before the attack  and she was unaware of  his  plans and devastated when she learned of the carnage while overseas  she said in a statement.

Still without motive frustrated police appeal for public's help in Vegas case