A note has been found in the Las Vegas gunman's hotel room, showing calculations of where to aim to maximise casualties.
The discovery was made by police who stormed his room last weekend and revealed in an American TV interview.
The piece of paper was found near the window that Stephen Paddock smashed before firing into crowds.
It comes a week on from the deadliest mass shooting in US history when 64-year-old Paddock opened fire on the crowd from the nearby Mandalay Bay hotel, killing 58 people.
Meanwhile, abandoned items which were strewn across the site of the Las Vegas massacre as people fled are being returned to their owners.
Thousands of people who were attending the Route 91 Harvest festival fled for their lives as Paddock slaughtered dozens before killing himself.
Police have spent the seven days since the shooting collecting evidence amid the thousands of items, some of them stained with blood.
"Whatever was dropped when people started running, those items we're collecting and we're going to provide back," Paul Flood, unit chief in the FBI's victim services division said at a news conference.
The items have been catalogued with detailed descriptions, and some have been cleaned of things including blood.
They are now being returned to people at a Family Assistance Centre at the Las Vegas Convention Centre, starting with a few sections of the concert scene.
"Just in general, the sheer size of the space, the amount of personal items that were left there, it's just a huge undertaking," Mr Flood said.
Las Vegas police have said they found 19 guns and several pounds of potentially explosive materials at the home that Paddock bought in early 2015, and where he lived with his girlfriend, Marilou Danley, who was in the Philippines during the shooting rampage.