SAN ISIDRO, PUERTO RICO - OCTOBER 15:  Uncollected debris stand near damaged homes in an area without electricity on October 15, 2017 in San Isidro, Puerto Rico. Puerto Rico is suffering shortages of food and water in many areas and only 15 percent of grid electricity has been restored. Puerto Rico experienced widespread damage including most of the electrical, gas and water grid as well as agriculture after Hurricane Maria, a category 4 hurricane, swept through.  (Photo by Mario Tama/Getty Images)
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SAN ISIDRO, PUERTO RICO - OCTOBER 15: Uncollected debris stand near damaged homes in an area without electricity on October 15, 2017 in San Isidro, Puerto Rico. Puerto Rico is suffering shortages of food and water in many areas and only 15 percent of grid electricity has been restored. Puerto Rico experienced widespread damage including most of the electrical, gas and water grid as well as agriculture after Hurricane Maria, a category 4 hurricane, swept through. (Photo by Mario Tama/Getty Images)
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SAN ISIDRO, PUERTO RICO - OCTOBER 15:  Uncollected debris stand near damaged homes in an area without electricity on October 15, 2017 in San Isidro, Puerto Rico. Puerto Rico is suffering shortages of food and water in many areas and only 15 percent of grid electricity has been restored. Puerto Rico experienced widespread damage including most of the electrical, gas and water grid as well as agriculture after Hurricane Maria, a category 4 hurricane, swept through.  (Photo by Mario Tama/Getty Images)
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SAN ISIDRO, PUERTO RICO - OCTOBER 15: Uncollected debris stand near damaged homes in an area without electricity on October 15, 2017 in San Isidro, Puerto Rico. Puerto Rico is suffering shortages of food and water in many areas and only 15 percent of grid electricity has been restored. Puerto Rico experienced widespread damage including most of the electrical, gas and water grid as well as agriculture after Hurricane Maria, a category 4 hurricane, swept through. (Photo by Mario Tama/Getty Images)
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MOROVIS, PUERTO RICO - DECEMBER 20:  A resident, whose home remains without electricity, watches as debris is removed on December 20, 2017 in Morovis, Puerto Rico. Barely three months after Hurricane Maria made landfall, approximately one-third of the devastated island is still without electricity and 14 percent lack running water. While the official death toll from the massive storm remains at 64, The New York Times recently reported the actual toll for the storm and its aftermath likely stands at more than 1,000. Puerto Rico's governor has ordered a review and recount as the holiday season approaches.  (Photo by Mario Tama/Getty Images)
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MOROVIS, PUERTO RICO - DECEMBER 20: A resident, whose home remains without electricity, watches as debris is removed on December 20, 2017 in Morovis, Puerto Rico. Barely three months after Hurricane Maria made landfall, approximately one-third of the devastated island is still without electricity and 14 percent lack running water. While the official death toll from the massive storm remains at 64, The New York Times recently reported the actual toll for the storm and its aftermath likely stands at more than 1,000. Puerto Rico's governor has ordered a review and recount as the holiday season approaches. (Photo by Mario Tama/Getty Images)
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SAN JUAN, PUERTO RICO - SEPTEMBER 30:  San Juan Mayor Carmen Yulin Cruz speaks to the media as she arrives at the temporary government center setup at the Roberto Clemente stadium in the aftermath of Hurricane Maria on September 30, 2017 in San Juan, Puerto Rico.  Puerto Rico experienced widespread damage including most of the electrical, gas and water grid as well as agriculture after Hurricane Maria, a category 4 hurricane, passed through.  (Photo by Joe Raedle/Getty Images)
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SAN JUAN, PUERTO RICO - SEPTEMBER 30: San Juan Mayor Carmen Yulin Cruz speaks to the media as she arrives at the temporary government center setup at the Roberto Clemente stadium in the aftermath of Hurricane Maria on September 30, 2017 in San Juan, Puerto Rico. Puerto Rico experienced widespread damage including most of the electrical, gas and water grid as well as agriculture after Hurricane Maria, a category 4 hurricane, passed through. (Photo by Joe Raedle/Getty Images)
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Residents of San Juan, Puerto Rico, deal with damages to their homes on September 20, 2017, as Hurricane Maria batters the island. 
Maria slammed into Puerto Rico on Wednesday, cutting power on most of the US territory as terrified residents hunkered down in the face of the island's worst storm in living memory. After leaving a deadly trail of destruction on a string of smaller Caribbean islands, Maria made landfall on Puerto Rico's southeast coast around daybreak, packing winds of around 150mph (240kph).
 / AFP PHOTO / HECTOR RETAMAL        (Photo credit should read HECTOR RETAMAL/AFP/Getty Images)
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Residents of San Juan, Puerto Rico, deal with damages to their homes on September 20, 2017, as Hurricane Maria batters the island. Maria slammed into Puerto Rico on Wednesday, cutting power on most of the US territory as terrified residents hunkered down in the face of the island's worst storm in living memory. After leaving a deadly trail of destruction on a string of smaller Caribbean islands, Maria made landfall on Puerto Rico's southeast coast around daybreak, packing winds of around 150mph (240kph). / AFP PHOTO / HECTOR RETAMAL (Photo credit should read HECTOR RETAMAL/AFP/Getty Images)
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(CNN) —  

Puerto Rico’s true death toll from Hurricane Maria remains elusive as the storm’s one-year anniversary approaches.

The island government raised the official death toll to 2,975 on Tuesday after maintaining for months that 64 people had died as a result of the storm.

But the higher figure, based on the findings of researchers from George Washington University in a study commissioned by the US commonwealth’s government, is only an approximation, not a concrete list of names, according to Gov. Ricardo Rossello.

“This number can change,” Rossello said. “It could be less, it could be more, as time passes.”

Here’s how the official death toll has changed since the storm touched down September 20 as a Category 4 hurricane:

6 to 13 deaths

01:59 - Source: CNN
Puerto Rico orders review of storm deaths

In the chaos after the storm, the island’s public safety director, Héctor M. Pesquera, said at least six people were killed.

Rossello told CNN two days after the storm hit that 13 people had died in the storm. That figure was based on reports from mayors on the island, but law enforcement authorities hadn’t confirmed the total, the government said.

Death toll rises to 34

00:46 - Source: CNN
Trump compares Puerto Rico deaths to Katrina

Nearly two weeks after Maria, President Donald Trump touched down for the first time and downplayed the devastation.

“Every death is a horror,” Trump said in early October before comparing Puerto Rico’s official death toll of 16 at the time to “a real catastrophe, like Katrina,” in which more than 1,800 people perished from the 2005 storm that ravaged New Orleans.

After Trump departed, the governor announced the death toll had risen to 34.

One of the conclusions of the George Washington University study was that officials did nothing to respond to public criticism and concerns about political motivations that surged when the official tally jumped to 34 shortly after Trump’s visit.

Funeral homes identify nearly 500 hurricane-related deaths

05:44 - Source: CNN
Puerto Rico's uncounted Hurricane Maria deaths

In November, CNN reporters surveyed 112 funeral homes across the island, about half the total. They found that funeral home directors identified 499 deaths considered to be hurricane-related.

Official toll climbs to 64

02:13 - Source: CNN
Rossello: Hell to pay if data not available

In December, public safety officials revised the official count to 64, adding some fatalities newly certified as indirect deaths related to the storm.

For instance, emergency personnel were unable to reach the home of a man who collapsed during the storm. Doctors had classified his death as natural, and it was not initially considered a storm-related death.

Other deaths later determined to be indirectly caused by the storm included a case of exposure to carbon monoxide, a suicide, a person run over by his own vehicle and a death from complications following a fall.

Estimated 1,052 ‘excess deaths’ after Maria

Also in December, The New York Times estimated 1,052 “excess deaths” occurred after Maria. Other media produced similar estimates.

Estimate of 4,645 deaths become rallying cry

01:58 - Source: CNN
CNN anchor presses PR governor on death count

In May, a team that included researchers from Harvard University published a study in the New England Journal of Medicine estimating 793 to 8,498 people died in Maria’s wake, a range that some academics have criticized as overly broad.

The study’s midpoint estimate – 4,645 deaths – became a rallying cry for activists upset by what they see as a lack of accountability for the scale of the catastrophe by officials in Puerto Rico and the United States.

An estimated 1,006 to 1,272 deaths

A research letter published this month in the medical journal JAMA estimated that between 1,006 and 1,272 people died in connection to the storm.

Puerto Rican government admits to 1,427 more deaths than ‘normal’

01:36 - Source: CNN
San Juan mayor: People died from neglect

The Puerto Rican government on August 8 quietly admitted the official toll was higher than its December tally.

In a report to Congress, the government said documents show that 1,427 more deaths occurred in the four months after the storm than “normal,” compared with deaths that occurred the previous four years.

The 1,427 figure also appeared in a draft of the report – “Transformation and Innovation in the Wake of Devastation” – which was published and opened for public comment July 9.

The revised figure was first “revealed” by the Puerto Rico government, according to the final report, on June 13, one day after officials were forced by a judge to release death records that CNN and the Centro de Periodismo Investigativo in Puerto Rico had sued to make public.

But officials at the time stopped short of updating the official death toll.