In a first-of-its-kind review of court documents, police reports, other public records and news accounts, Reuters compiled the most comprehensive public accounting to date of deaths and litigation that followed police use of Tasers.

In all, reporters documented 1,005 people who have died in the United States following encounters with police in which Tasers were used either on their own or, more often, as part of a larger mosaic of force. In at least 153 of those cases, Reuters found, coroners or medical examiners cited the Taser as a cause or contributing factor in the death.

Among the 1,000-plus fatalities, Reuters found that wrongful death lawsuits were filed in at least 442 of the incidents. Nearly all the suits – 435 – were filed against police and the municipalities that employ them. Taser International, the manufacturer, was named as a defendant in 128 cases. There were three lawsuits, from 1983 to 1987, against Taser Industries Inc, a business Taser International acquired in 2003. The company recently changed its name to Axon Enterprise Inc.

Reuters conducted hundreds of interviews with current and former police officials, lawyers involved in lawsuits involving Tasers, academics and other independent experts, relatives of people who died and Taser International.

Here are the sources of information and the methodologies behind the project’s key findings:

Deaths following Taser shocks:

To identify these cases, Reuters examined thousands of court records, police reports and news stories from 1983, the earliest mention of a fatality identified in a police encounter where a Taser was used, through July 31, 2017. Legal records were searched using Westlaw, a database of legal filings owned by Thomson Reuters, as well as Lexis and Pacer, two other databases of legal documents. Reuters also researched news accounts nationwide.

The news agency reviewed reports by other organizations that tracked deaths in incidents where Tasers were used, including the human rights group Amnesty International, and advocacy websites Truth Not Tasers and Fatal Encounters. Reuters used stricter criteria than those organizations to decide which cases to count, so our tally does not include more than three dozen deaths those organizations identified. Nevertheless, Reuters’ listing of 1,005 deaths is 44 percent larger than the 700 reported by Amnesty at the end of 2016.

Among the cases Reuters opted not to include were those in which a person was shot with a firearm after being stunned by a Taser. The only exceptions were six cases in which the Taser use was cited in a wrongful death lawsuit or an autopsy specifically ruled out the gunshot as the primary cause of death. Reuters also counted only those deaths in which it could identify the victim and confirm through court documents, police reports, other public records or credible media accounts that a Taser was used. If Reuters was unable to confirm Taser use, the incident wasn’t counted. For example, some lists of fatalities involving Tasers include Mark Lee, who died in a 2006 encounter with police in Rochester, New York. News reports said police disputed the family’s assertion that a Taser was used. Reuters omitted the case after contacting the family’s lawyer, who said the Lees were ultimately unable to prove “definitively” a Taser was used.

Reuters included 17 cases in which people died from choking on bags of drugs while being stunned. The news agency surveyed a number of pathologists on whether a Taser shock would increase the likelihood of choking under those circumstances. They offered no clear consensus but most suggested it was possible.

Taser said the only deaths that can be attributed to its stun guns involve 24 cases in which the person died from secondary injuries, such as falls or fires caused by the Taser.

Taser International also tracks deaths in police incidents where its weapons were used and catalogs that information in a “database of in-custody deaths proximal to Taser use,” according to court testimony from company officials. The company declined to share the data with Reuters.

Seventeen of the deaths on the Reuters list occurred before Taser International acquired the technology from its inventor in 1993 and began marketing its first version of the weapons.

Autopsy findings:

Taser International has long argued that its weapons are almost never to blame when someone dies after being stunned. Reuters sought autopsy results and cause-of-death rulings for all the 1,000-plus deaths. Many states restrict access to autopsy records and do not release them publicly.

But Reuters was able to collect official cause-of-death rulings for more than 70 percent of the deaths it identified – 712 cases. Tasers were listed as a cause of death or a contributing factor or condition in 153 of those cases. Most of the other autopsies cited a combination of heart and medical conditions, drug use and various forms of trauma.

Many of the autopsies reviewed by Reuters listed the cause of death as “multi-factorial.” The autopsies that cited a Taser shock often included it as one of several components of their ruling.

To collect the autopsies, Reuters filed public records requests in dozens of states and scores of counties. In 278 cases, Reuters obtained full autopsies. In 348 others, medical examiners, coroners or other local officials provided the cause-of-death findings, often with contributing factors or conditions, in writing or by reciting the information over the phone.

In 86 cases, Reuters obtained cause of death information through other official records, such as reports from state investigations or court documents.

Wrongful death lawsuits:

Reuters set out to identify all wrongful death suits filed in cases where someone died after being stunned with a Taser during a police encounter. The process involved constructing a series of queries using different parameters to search Westlaw, Lexis and Pacer. Reuters also combed through state court filings in dozens of states to find lawsuits. Those searches yielded several thousand suits in which a stun gun was mentioned.

Reporters then reviewed all the search results and identified 442 cases in which Tasers factored into a wrongful death claim, sifting out injury suits and the vast majority of suits in which the subject was shot with a firearm. In 120 of the 442 cases, or 27 percent, the Taser was the only force alleged in the claim; in the remaining 322 cases, the stun guns were alleged to have been part of a broader array of police force.

Most of those cases were filed in federal court. Because not all state courts are included in Westlaw and other legal databases, the 442 figure likely omits some state cases.

Settlements and awards:

More than three-fifths of the 366 concluded lawsuits against governments, or 232, resulted in judgments or settlements for the plaintiffs: 220 settlements and 12 judgments. Reuters was able to determine the payouts in 193 cases, totaling $172 million paid by cities and their insurers. That dollar figure does not include three dozen cases in which settlements remained confidential or were unavailable.

The settlement and judgment totals were obtained by filing public records requests with dozens of municipalities. In some cases, government agencies declined or did not respond to requests for data. In some of those instances, Reuters was able to confirm settlement amounts through court records, lawyers or media reports.

Because Reuters was not able to identify settlement amounts in dozens of cases where terms weren’t disclosed, the actual total of payouts by local governments and their insurers is certainly higher than $172 million.

Taser declined to share detailed information on which cases it has settled and how much it has paid to satisfy those settlements.