(CNN) A newly-ordered government review of the deaths in Puerto Rico since Hurricane Maria is already coming under fire because the man leading it has staunchly defended an official tally widely believed to be low.

An executive order signed by Gov. Ricardo Rosselló on Thursday directed the island's public safety secretary, Héctor M. Pesquera, to head the 90-day review of the death toll since the September storm.

The secretary, who has overseen the official count, has defended it based on the information received to date -- despite mounting evidence that Puerto Rico has vastly undercounted storm-related deaths.

The government maintains 64 people died as a result of the hurricane, which slammed into the Caribbean island, tearing roofs from homes and cutting power and water service for millions of people.

"As part of the recovery process, it is important to guarantee transparency in the damages caused to the lives and safety of our citizens," Rosselló said in a statement.

JUST WATCHED Puerto Rico orders review of storm deaths Replay More Videos ... MUST WATCH Puerto Rico orders review of storm deaths 01:59

The review comes after investigations by CNN and other news outlets as well as analysis by academics have called into question the official death toll.

Alexis Santos, a Pennsylvania State University demographer who conducted a statistical assessment of reported deaths on the island, said Pesquera's involvement "could put into question the transparency of the process."

"The executive order gives Pesquera the authority to establish the process and he has ... been resistant to accepting counts and has been confrontational with the press and academics when discussing this topic," Santos said via email Friday.

Pesquera's press officer did not immediately respond to a request for comment.

In October, the public safety secretary told CNN that the suggestion of political meddling in the death toll was "horses**t."

"You think I care what the government of the United States thinks about the body count? I don't care," Pesquera said. "I could care less what's less embarrassing."

In addition, Santos said Rosselló's executive order does not "give people a retroactive right for purposes of insurance or any rights they may have if the death is determined to be associated with Hurricane Maria." This will prevent family members from applying for the federal government reimbursement for funeral expenses.

The analysis by Santos and Jeffrey Howard, a demographer and epidemiologist at the US Department of Defense, found an estimated 518 more people died in Puerto Rico in September 2017, the month of Hurricane Maria, than died during previous Septembers on the island.

The estimate was not an accounting of individual hurricane deaths, Howard said, but instead a statistical look at how many people died the month of the hurricane versus the number that normally would be expected to die in that month. It's unclear when the extra deaths occurred that month. Hurricane Maria hit on September 20.

Still, the demographers' estimate seemed to be substantiated by the CNN survey of 112 funeral homes in Puerto Rico. As part of that investigation, funeral home directors said they saw 499 deaths in the month after the hurricane -- September 20 to October 19 -- that they claim are related to the storm and its aftermath.

John Mutter, a professor at Columbia University who researched deaths following Hurricane Katrina, told CNN Friday that Pesquera's involvement in the review posed a conflict.

"At best, he should be an ex-officio member, there to provide information," Mutter said. "Instead, he will defend what he did. No one will believe the outcome, no matter what it is."

Rosselló's statement said Pesquera will work "in coordination with the Demographic Registry and the Bureau of Forensic Sciences" in reviewing the deaths.

"Pesquera's involvement certainly reduces the trust of the people in this revision," Santos said. "In the event the revision provides contradictory evidence, he will be in the difficult position of accepting he has been wrong for the past three months."