Ever since construction crews dug up the ornate, 19th century casket of a blond-haired toddler holding a single red rose from beneath a San Francisco home the question remained: Just who was this little girl?

In the weeks since workers unearthed the small, airtight coffin adorned with two glass windows during a home renovation last month, a group of investigators and scientists have come forward offering their assistance — pro bono — to help identify the girl, who is estimated to be about 3 years old. The head of the operation, a Billy the Kid expert from New Mexico, said he’s already narrowed down a name by rummaging through old newspaper clippings and official records.

“We’ve got a strong possible, but we’re looking for a map,” said Steven Sederwall, a retired cop who is now a private investigator. “We’ve got an infant that fits the description.”

Before releasing the girl’s name, Sederwall and his handful of assistants, including some in the Bay Area, hope to find a burial plot map for the Odd Fellows Cemetery, which operated between 1860 and 1890, and compare it to a current city map to see if the locations match. The problem: many death records and other vital documents from the 1800s were lost during the 1906 earthquake and fire.

“We may not be able to (ID her),” Sederwall said. “You just have to work with what you’ve got.”

On Friday, a forensic specialist will pluck 10 locks of the girl’s hair and they will be sent to a UC Davis anthropology professor who will create a DNA profile and potentially compare it against living relatives.

“You can also look at the chemical signatures,” said Professor Jelmer Eerkens, who normally deals with older skeletal remains in his studies. “From that you could tell her diet, where she was living.”

Eerkens, like many of the volunteers, read about the girl’s story online and offered to help.

“It kind of grabbed me because I have a granddaughter that’s just a little bit older,” said Sederwall, who previously gained attention by conducting a crime scene investigation of the Billy the Kid jail break scene and authenticating a rare photo of the Old West outlaw.

The girl, renamed Miranda Eve for now, was apparently left behind when the other 26,000 remains from the Odd Fellows cemetery in the Richmond District were moved to Colma’s Greenlawn Memorial Park around 1920.

When contractors found the coffin under the concrete floor of a homeowner’s garage, the resident turned the ornate casket over to the Garden of Innocence, a charity that buries unclaimed children. On Saturday, the nonprofit plans to bury the girl at Greenlawn in a 10 a.m. ceremony open to the public.

“It is our hope that maybe, just maybe, her family was moved there too and we might be able to place her near where her mother might be,” Garden of Innocence founder Elissa Davey said.

While Miranda has kept in a refrigerated Fresno facility, Davey and her family spent the weekend building a new wooden casket for the girl. They plan to place the original coffin inside the new one and lay her to rest — if they can get a burial permit.

Santa Cruz Memorial, which has donated mortuary services, is working to secure it, but with no name or death certificate, there are obstacles.

“We have to prove our case for it with pictures and documents that I have put together to get the permit,” Davey said.

A San Mateo County official said Tuesday it is illegal to issue a burial permit without a death certificate. The state’s department of Vital Records now is mulling a decision on what can be done, but a state spokesman said he was checking on the case Tuesday.

Meanwhile, Sederwall continues to lead the research team, which has learned the transfer of bodies to Colma was quite haphazard — as simple as digging trenches and moving the coffins located by shovel strikes.

“I have a strong suspicion there’s more bodies out there,” he said.