LAS VEGAS (AP) — 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.

“We still do not have a clear motive or reason why,” Clark County Undersheriff Kevin McMahill said. “We have looked at literally everything.”

The FBI announced that billboards would go up around the city asking anyone with information to phone 800-CALL-FBI.

“If you know something, say something,” said Aaron Rouse, agent in charge of the Las Vegas FBI office. “We will not stop until we have the truth.”