In response to mounting accusations of a cover-up, the government ordered an independent investigation and on December 18, 2017, contracted a study of the death toll by the Milken Institute School of Public Health.

On August 28, the Government of Puerto Rico revised the official death toll to be 2,975 people, ranking Maria as one of the deadliest hurricanes in United States history.

The official estimate is based on a study commissioned by the governor of Puerto Rico,[3] where researchers at George Washington University developed statistical models showing the number of excess deaths for the time period between September 2017 and February 2018 to be between 2,658 and 3,290 (with a 95 percent confidence interval).

[4] In the decade preceding Maria, Puerto Rico suffered from major financial decline and crippling debt from a combination of poor fiscal management and changes in federal tax policy.

A change in federal taxation policy prompted an exodus of lucrative business and reduced tax revenue; poverty rates reached 45 percent.

[7] While recovery efforts remained underway in Texas and Florida for Harvey and Irma, respectively, Maria struck Puerto Rico on September 20 as a high-end Category 4 hurricane.

[10] The hurricane inflicted catastrophic damage island-wide, decimating the power grid, crippling road infrastructure, and leaving the majority of people without access to clean water.

[11] The Federal Emergency Management Agency had little time to prepare and respond, and had shipped out many of the supplies it had stored on Puerto Rico to assist recovery from Irma in the US Virgin Islands.

The agency admitted logistical failures, personnel shortages, and communication troubles with the local government vastly hampered their ability to assist in recovery.

Injured persons or those in need of regular medical care (such as dialysis) were unable to access emergency services for prolonged periods of time.

[12] In the months following Maria, the official death toll relayed from the Government of Puerto Rico came into question by media outlets, politicians, and investigative journalists.

Deaths related to power outages at Manatí Medical Center were not sent to San Juan for examination according to executive director José S. Rosado.

[14] In an October 12, 2017 public letter to the Department of Homeland Security, Representatives Nydia Velázquez and Bennie Thompson complained that the death toll was underreported, either intentionally "to portray relief efforts as more successful than they are", or "due to a lack of capacity on the island", and requested that DHS immediately evaluate the accuracy and methodology of the enumeration.

[14] During a press conference on October 3, 2017, President Donald Trump applauded the initial low death toll—at the time the government only certified 16 deaths—and claimed it was nothing like "a real catastrophe like [Hurricane] Katrina" in 2005 with thousands dead.

San Juan Mayor Yulín Cruz harshly criticized Trump as "killing [Puerto Ricans] with the inefficiency [of relief efforts].

[23] By the end of November, the Puerto Rican government maintained that their report of 55 fatalities was the most accurate despite ample contrary evidence collected by media and investigative journalists.

[30] On June 4, Superior Court Judge Lauracelis Roques Arroyo ruled the requested information to be public record and ordered the data to be published within a week.

[31] The government filed a motion to delay the release of these records on June 12, citing more time was needed to compile the information due to limited staff and budgeting.

The combined effects of Irma in early September and Maria left the entire island without power, the majority without access to clean water, and crippled road infrastructure.

[36][37] On August 28, 2018, Governor Rosselló acknowledged the results of the George Washington University study and revised the island's official death toll to 2,975 people.

Then, a long time later, they started to report really large numbers, like 3000 This was done by the Democrats in order to make me look as bad as possible when I was successfully raising Billions of Dollars to help rebuild Puerto Rico.

[39][40] He claimed "3000 people did not die in the two hurricanes that hit Puerto Rico"—referring to Irma and Maria, and that these reports of large numbers of deaths were caused by "bad politics" pushed by Democrats to smear his image.

[46] Multiple Republican politicians from Florida denied Trump's claims, including Senator Marco Rubio, Governor Rick Scott, and former Representative Ron DeSantis.

Significant spikes in causes of deaths compared to the two preceding Septembers included sepsis (+47%), pneumonia (+45%), emphysema (+43%), diabetes (+31%), and Alzheimer's and Parkinson's (+23%).

[25] Two scientists at Penn State University, Alexis Santos and Jeffrey Howard, estimated the death toll in Puerto Rico to be 1,085 by the end of November 2017.

[50] Extrapolating the results to the entire population of Puerto Rico would suggest that between 793 and 8,498 excess deaths (with a 95 percent confidence interval) occurred in the aftermath of the hurricane.

Donald Berry at the University of Texas MD Anderson Cancer Center stated, "The results are statistically weak and nearly useless, at least insofar as number of deaths is concerned ...

On August 27, 2018, the university published its results, indicating that 2,658–3,290 excess deaths (with a 95 percent confidence interval)[57] occurred between September 2017 and February 2018, primarily driven by the effects and aftermath of Hurricane Maria.

These 64 fatalities occurred due to the direct results of Hurricane Maria, namely drowning and blunt-force trauma from collapsed buildings and airborne debris.

[18][4] The results provided "blistering criticism" of Rosello and his government for inadequate preparedness and personnel training for crisis and emergency risk communication.