File picture: Brendan McDermid/AP

Washington - The firefighter found Richard Dabate on the floor of his kitchen, where he had made a desperate 911 call minutes earlier, court records show. Bleeding and lashed to a chair with zip ties, the man moaned a chilling warning: "They're still in the house."

Smoke hung in the air, and a trail of blood led to a darkened basement, as Connecticut State Police swarmed the large home in the Hartford suburbs two days before Christmas in 2015.

Richard, 41, told authorities a masked intruder with a "Vin Diesel" voice killed his wife, Connie, in front of him and tortured him. Police combed the home and town of Ellington but found no suspect.

With no witnesses other than Richard Dabate, detectives turned to the vast array of data and sensors that increasingly surround us. An important bit of evidence came from an unlikely source: the Fitbit tracking Connie's movements.

Others from the home's smart alarm systems, Facebook, cellphones, email and a key fob allowed police to re-create a nearly minute-by-minute account of the morning that they said revealed Richard's story was an elaborately staged fiction.

Undone by his data, Richard was charged with his wife's murder. He has pleaded not guilty.

The case, which is in pretrial motions, is perhaps the best example to date of how Internet-connected, data-collecting smart devices such as fitness trackers, digital home assistants, thermostats, TVs and even pill bottles are beginning to transform criminal justice.

The ubiquitous devices can serve as a legion of witnesses, capturing our every move, biometrics and what we have ingested. They sometimes listen in or watch us in the privacy of our homes. And police are increasingly looking to the devices for clues.

The prospect has alarmed privacy advocates, who say too many consumers are unaware of the revealing information these devices are harvesting. They also point out there are few laws specifically crafted to guide how law enforcement officials collect smart-device data.

Andrew Ferguson, a University of the District of Columbia law professor, says we are entering an era of "sensorveillance" when we can expect one device or another to be monitoring us much of the time. The title of a law paper on the topic put the prospect this way: "Technology is Killing Our Opportunity to Lie."

The business research company Gartner estimates 8.4 billion devices were connected to the internet in 2017, a 31 percent increase over the previous year. By 2020, the company estimates there will be roughly three smart devices for every person on the planet.

"Americans are just waking up to the fact that their smart devices are going to snitch on them," Ferguson said. "And that they are going to reveal intimate details about their lives they did not intend law enforcement to have."

Undone by his data

The Dabates' yellow Colonial was festively decorated with wreaths on the windows the morning of December 23, 2015. Richard, Connie and their two boys, ages 6 and 9, bustled around getting ready for the day.

To many of their acquaintances, the family appeared to be an ordinary one in a quiet bedroom community. Richard was a network administrator, and Connie worked as a pharmaceutical sales representative.

Joann Knapp, a former neighbor of the Dabates, fondly recalls Connie popping over to her house to ask her out for walks while Knapp was having a difficult pregnancy. Knapp said Connie and Richard appeared to have a happy - even passionate - marriage.

"They couldn't keep their eyes off each other," Knapp said. "It was a look that you would want."

But behind that public face, Connie's killing would reveal a darkly tangled relationship and a major secret.

Richard and his attorney did not respond to requests for comment. Richard gave a detailed - but shifting - account of Connie's killing to detectives over six hours on the day of the slaying. It is contained in his arrest warrant.

On the drive to work that morning, Richard said, he got an alert on his phone that the home's alarm had been triggered. He said he shot an email to his boss and returned home, arriving there between 8.45am and 9am.

Richard told police he heard a noise on the second floor and found a hulking intruder wearing camouflage and a mask inside the walk-in closet of the master bedroom. The intruder demanded his wallet at knifepoint.

Soon after, Connie returned home from an exercise class; Richard told investigators he yelled at her to run. Connie fled into the basement, and the intruder followed.

When Richard arrived on the lower level, he made his way through darkness, finding the man pointing a gun at Connie's head. Richard said that the gun was his own and that Connie must have removed it from a safe to defend herself.

Richard said he charged but heard a deafening blast and fell. When he got up, Connie was slumped on the ground. Police would later determine the gunshot hit her in the back of her head.

The intruder disabled Richard and then zip-tied one of Richard's arms and one of his legs to a folding chair, according to the account.

The intruder jabbed Richard with a box cutter. The man also started a fire in a cardboard box using a blow torch, which he then turned on Richard's ankle.

Richard told investigators he saw an opening: He jammed the blow torch in the man's face and singed it. The intruder ran out.

Richard said he crawled upstairs with the chair still attached, activated the panic alarm, called 911 and collapsed. The firefighter found him soon after.

The chaotic scene inside the Dabate home had all the hallmarks of a home invasion, but a few details would prompt investigators to take a closer look.

Dogs brought in to track the suspect could find no scent trails leaving the property and circled back to Richard, according to arrest records. Richard also aroused suspicion when detectives asked whether their probe would reveal any problems between him and Connie.

He took a deep breath and offered: "Yes and no."

Richard told a bizarre story. He said that he had gotten a high school friend pregnant and that it was Connie's idea. He said the three planned to co-parent the child, since his wife wanted another baby but could not have one for health reasons.

Later, Richard changed his story, saying that the pregnancy was unplanned and that he had a romantic relationship with the friend. Detectives found no evidence Connie knew of the pregnancy.

"This situation popped up like a frickin' soap opera," Richard told detectives.

The admission pointed toward a possible motive for Connie's killing, but it would be the data detectives uncovered that would give them evidence to conclude his story was a lie.

Detectives had noticed Connie was wearing a Fitbit when they found her body.

They requested the device's data, which showed she had walked 1,217 feet after returning home from the exercise class, far more than the 125 feet it would take her to go from the car in the garage to the basement in Richard's telling of what happened.

The Fitbit also registered Connie moving roughly an hour after Richard said she was killed before 9.10am. Facebook records also cast doubt on Richard's timeline, showing Connie had posted as late as 9.46am.

Detectives would also come to doubt that Richard left home that morning, after examining data from his home alarm system and his email account.

Records indicate he used a key fob to activate his home alarm from his basement at 8.50am and then disabled it at 8.59am from the same location.

Richard also told investigators he emailed his boss from the road after getting the alert about the alarm. But records from his Microsoft Outlook account showed he sent the email from the IP address associated with his home.

Combined, the data punched major holes in Richard's story. Police obtained an arrest warrant for him in April.

The high school friend of Richard's told authorities he had said he planned to serve divorce papers on Connie the week she was killed. Richard had texted her the night before Connie's death: "I'll see you tomorrow my little love nugget."

The Dabate case is just one of a handful in which law enforcement officials have resorted to smart-device sleuthing.

In September 2016, an Ohio man told authorities he awoke to find his home ablaze, but police quickly suspected he set the fire himself. They filed a search warrant to get data from his pacemaker.

Authorities said his heart rate and cardiac rhythms indicated the man was awake at the time he claimed he was sleeping. He was charged with arson and insurance fraud.

Prosecutors in a 2015 Arkansas murder case sought recordings from the suspect's Amazon Echo when a 47-year-old man was found floating in the suspect's hot tub after a night of partying. Authorities thought the voice-activated assistant may have recorded valuable evidence of the crime.

Amazon.com challenged the search warrant in court, saying that the request was overly broad and that government seizure of such data would chill customers' First Amendment rights to free speech. But the challenge was eventually dropped because the suspect agreed to allow Amazon to turn over the information. (Amazon chief executive Jeffrey Bezos is the owner of The Washington Post.)

Virginia State Police Special Agent Robert Brown III of the High Technology Division said the current trickle of such smart-device cases will probably soon become a flood.

"It will definitely be something in five or 10 years, in every case, we will look to see if this information is available," Brown said.

Amazon and Fitbit said in statements that they won't release customers' data to authorities without a valid legal demand, but they declined to say how many such requests they have received from law enforcement.

"Respect for the privacy of our users drives our approach," Fitbit said in its statement.

Ferguson, the law professor, said a case before the Supreme Court could be key in determining how exposed smart-device data is to searches by law enforcement.

In 2011, investigators in Detroit obtained months of cellphone location data on a suspect in a robbery investigation without a search warrant. Timothy Carpenter was later convicted, in part on this information gleaned from cellphone companies.

Carpenter is arguing in his appeal that such cellphone location data is so powerful it should be covered by the protections of the Fourth Amendment and that police should be required to get a search warrant to obtain it.

Courts have long held that people who voluntarily disclose information to a bank, cellphone company or other third party have no reasonable expectation of privacy. Ferguson said that since many smart devices transfer data to company servers, this third-party doctrine could apply to them, as well.

Ferguson said a ruling against Carpenter might clear the way for authorities to seek smart-device data stored on those servers without a warrant.

"In a world of truly ubiquitous connectivity where we are recording our heartbeat, our steps, our location if all of that data is now available to law enforcement without a warrant, that is a big change," he said. "And that's a big invasion of what most of us think our privacy should include."