"I called her up immediately and she said, 'Relax, we shouldn't worry about it".
It was through his gambling that Paddock reportedly met Danley, when she was working as a hostess at a casino in Reno, Nevada, several years ago.
News that Paddock was the man responsible for killing 59 people and wounding more than 500 was shocking to Alarcon.
The latest revelation came Tuesday afternoon when police said the gunman set up cameras inside his hotel suite and in the hallway.
The woman said Danley is "a good person" who would've stopped Paddock had she been there.
Danley, 62, who had traveled to Hong Kong on September 25, could fill in some of the blanks when she returns to the US on Wednesday, the officials said.More news: Leigh Griffiths Goal Gives Celtic A Crucial Lead In Anderlecht
Clark County Undersheriff Kevin McMahill said the shooting spanned between nine and 11 minutes.
They also believe that Danley knew nothing of Paddock's plan, and that she was sent away so she can not interfere with his plan. "She is now a person of interest".
Paddock smuggled a cache of 23 weapons into the hotel, including AK-47s and "bump stock" devices to make his guns fully automatic, in 10 separate bags.
She married American Geary Danley in 1990, and they registered their marriage in Nevada.
According to Australian authorities, the Filipino-born Danley has Australian citizenship and has family there.
The Las Vegas shooter's girlfriend has voluntarily returned to the USA from the Philippines as authorities probe for any possible links to the case.
Danley, 62, is a Philipinnes native and investigators say she likely traveled there to visit family.More news: Nuclear accord with Iran in USA interest: Mattis
Stephen Paddock, a reputed heavy gambler, allegedly wired almost $100,000 to the Philippines prior to the shooting in which he took his own life. She was out of the country during the shooting, police said.
He had no criminal record and was not known to police, who have yet to state his motives for the mass shooting, the worst in U.S. modern history.
Investigators have plenty of evidence but nothing yet that points to a motive in the shooting.
No motive has emerged yet for the deadly shooting spree by Paddock, a wealthy, 64-year-old retired accountant who liked to gamble for high stakes and owned a comfortable home at a golf course retirement community near Las Vegas.
Public records on Paddock point to an itinerant existence across the West and Southeast parts of America, including stints as an apartment manager and anaerospace industry worker.
They lived together in Mr Paddock's property in Babbling Brook Court, a two-bedroom home worth $396,000 (£297,554). Police said they're investigating the source of the leaked photos.More news: Ukip: A timeline of the party's turbulent history