Boston police are carrying a huge backlog of nearly 1,000 unsolved murders in the Roxbury, Mattapan and Dorchester neighborhoods dating to 1970, according to a Herald review that also found signs of shoddy record-keeping that a department spokesman refused to discuss.

The 45-year burden of cold cases in the city’s three hardest-hit neighborhoods was released in response to a public records request by advocate Mary Franklin, whose husband’s 1996 murder remains unsolved.

The 925 cases are riddled with holes where critical information is lacking, the review found. The records show:

• Mattapan, Dorchester and Roxbury have a total of 925 unsolved murders on the books between April 1970 and last month.

• The incomplete files Boston police turned over have hundreds of missing victim identifiers including 299 instances where the race of the victim was left blank; 119 instances where the age of the victim was missing, and 11 instances where the victim is listed as a Jane or John Doe.

Mary Ann Davis, 64, of Hyde Park, the grandmother of one murder victim, said she’s horrified by the nightmare of her grandson’s killer walking free.

“It’s upsetting and makes me feel afraid. If he killed my grandson, he has no fear killing someone else. That’s just another life. … He’s still walking around on the street,” said Davis, whose grandson, Jordan Miller, was fatally shot in June 2013 on Cummins Highway just weeks before his 21st birthday.

“I feel just awful. Some days are better, some days are worse,” Davis said.

When asked yesterday if Boston police have more accurate records, BPD spokesman Lt. Michael McCarthy said, “We have case files on every single homicide in the city that has happened. Beyond that, we’re not responding to something Mary Franklin has to ask or the Herald has to ask about Mary Franklin.”

The city’s crisis in unsolved murders was first reported by the Herald last year, in a special report that revealed 336 unsolved murders between 2004 and 2013 remained on the books.

Franklin is the head of Women Survivors of Homicide Movement, a group that sprang from that report.

The series also showed more than two-thirds of the city’s murders were committed in Roxbury, Mattapan and Dorchester; and that black men were slain at 10 times the rate of white men. But proportionately, police solved about half as many murder cases in which the victim was black.

The stunning cold-case revelation comes as both Mayor Martin J. Walsh and Boston Police Commissioner William B. Evans have pledged to the loved ones of unsolved murder victims that these cases will not be forgotten.

Walsh this month designated Oct. 15 “Unsolved Homicides Awareness Day” and raised a flag at City Hall Plaza with Evans, to bring awareness to the city’s cold cases.

“We will never give up seeking justice for you,” Walsh told women in Franklin’s group. He also said BPD is committed to solving every murder in every neighborhood.

Evans said at that ceremony, “We never forget your loved ones. … We never forget any victim of homicide out there.”

“We want to bring to justice those who are responsible for the senseless violence in the city of Boston,” he said.