RELATED: Slain Italian police officer put to rest as Bay Area men face possible murder charges
A source close to the Elder family has concerns about leaks from the police about this case, and about conflicting accounts of his alleged confession.
Here's what we know from court documents about what happened, step-by-step.
On Tuesday, Dan Noyes stopped at each of the locations from that night - the spot where the officer was mortally wounded, the hotel room where police say the young men hid the knife behind a ceiling panel, the police station where the teens were interrogated, even the home of a man police identified as a drug dealer who interacted with the teens.
RELATED: Finnegan Lee Elder: Who is the American student accused of fatally stabbing Italian officer Mario Cerciello Rega?
Elder's family tells the ABC7 I-Team they arranged this solo trip to Italy for him, hoping he would have a break from his circle of friends.
They booked one night at the Meridian Hotel hotel in Rome so he could meet 18-year-old Gabe Natale, who had been visiting his grandfather, who lives near Rome. The young men were 2018 graduates of Tam High in Mill Valley.
Finn Elder’s hotel room in Rome sealed off with evidence tape. Police say he stashed the murder weapon behind a ceiling panel in the room. I was able to look inside a nearby room. No drop down ceiling in the main part, but there are a few panels in the entryway. #ABC7now pic.twitter.com/fUNbDDEp93— Dan Noyes (@dannoyes) July 30, 2019
Newly-released court documents state Elder and Natale went to Trastevere, a popular neighborhood with bars and restaurants this past Friday, allegedly looking for cocaine.
According to court records, they contacted a local, the man on the bicycle shown on surveillance video, and he introduced them to a dealer who took their money.
But when the alleged drug deal went bad, the California teens reportedly ran away with the backpack from the man on the bicycle.
I’ve been able to find the address of the man police identify as the drug dealer involved in the incident before the Italian police officer’s death. About to knock on his door. #ABC7now pic.twitter.com/CSuGZGdr66— Dan Noyes (@dannoyes) July 30, 2019
The backpack owner called police and they listened as he called Natale and Elder using WhatsApp. They arranged a meeting at a street corner. At a news conference on Tuesday, the Italian police commander said they respond to complaints like this often - people asking for ransom for what they stole, and that's why two officers responded in plain clothes.
In court records, the surviving police officer states they showed their police ID cards and identified themselves as law enforcement, or "carabinieri" in Italian.
Police say Gabe Natale, who speaks Italian, told them he doubted the men were officers and the fight began, with Natale striking one officer with his fists. They also say Elder later admitted he stabbed the second officer.
Italian police say when they told the Bay Area suspects that the police officer was dead, Gabe Natale didn’t believe it, asking twice if it were true, and Finn Elder started crying. Police say Elder admitted stabbing the officer. #ABC7now pic.twitter.com/wSXLAyYSE0— Dan Noyes (@dannoyes) July 30, 2019
On Tuesday, the police commander said the surviving officer didn't have time to react, and did not want to shoot the suspects in the back as they ran away.
In court documents, Officer Andrea Varriale said he saw his partner, Mario Cerciello Rega "bleeding abundantly from his chest. Before falling on the ground he said, 'They stabbed me.'"
Cerciello Rega died from 11 stab wounds later at the hospital.
Investigating step by step in Rome, what led to the death of Italian police officer. Two young men from Bay Area being held. Four police cars nearby but did not have time to respond. Here’s why #ABC7now pic.twitter.com/tysBWyxiDc— Dan Noyes (@dannoyes) July 30, 2019
Surveillance video shows the fatal encounter with police lasted less than four minutes. A porter and a doorman back at the hotel spotted the teens running back, after 3 a.m.
From surveillance video, police were able to track Natale and Elder back to the hotel, Room 109. In court documents, police say they found the murder weapon: a 7-inch US Marine style knife drenched in blood, hidden behind a ceiling panel. Police released a photograph of the knife on Tuesday.
Police also said on Tuesday that the deceased officer forgot to bring his gun that night and that Finn Elder brought the knife on the plane from the U.S.
The I-Team broke the news that Finn Elder's father, Ethan, is heading to Rome, expected to arrive Wednesday morning.
The I-Team's Dan Noyes is in Italy covering the investigation for ABC7. Follow his updates on Twitter and Facebook.
Go here for more information and updates on the killing of Mario Cerciello Rega.