NEW YORK (CBSNewYork) — A veil of secrecy has been lifted, finally revealing the status of the city’s investigation into Ultra-Orthodox Jewish schools and how they fare preparing students for lives beyond their own communities.

Three years after the start of the probe into secular education at yeshivas, a letter from New York City Schools Chancellor Richard Carranza to the state’s education commissioner notes some progress, reports CBS2’s Dave Carlin.

The letter also notes progress has been limited, taking to task that 15 of about 30 schools slated for visits, where investigators never went in.

“That to me is not an acceptable state of affairs,” Mayor Bill de Blasio said.

De Blasio, who has been criticized for not pursuing this aggressively enough, said the hold-out yeshivas cannot hide.

“We suddenly got a communication saying some of them now will invite our DOE officials in,” the mayor said.

MORE: Legal Fight Underway To Make Yeshiva Students Meet NY State Standards

Attorney Avi Schick and other supporters of the yeshivas, including Parents for Educational and Religious Liberty in Schools, or PEARLS, said the curriculum has changed to include more reading and math, with new books for more than 10,000 students.

“Access was never denied by those schools and access will never be denied by those schools,” Schick said.

CBS2’s Carlin went to talk to Chancellor Carranza about his letter, which he said is a simple update and in no way closes the book on the investigation.

“The investigation is still ongoing,” Carranza said.

Carlin then said, “If someone were to read that letter and say, ‘Wow, it looks like roadblocks were put in your way,’ would you say that’s true?”

“I think it’s important that we have an opportunity to go to visit the schools that have not been visited yet,” Carranza said.

The city investigation began in 2015 with complaints from the group Young Advocates For Fair Education, or YAFFED, headed by Naftuli Moster, who said his own yeshiva education was shockingly incomplete.

“To this day, absolutely, I’m still experiencing major gaps and challenges as a result,” Moster said. “If yeshivas get so much funding from taxpayer dollars, there have to be strings attached.”

When asked how much government oversight is appropriate in his opinion, Rabbi David Zwiebel said, “Government has to regulate with a very loose hand, not a very heavy hand. That’s part of what we’re fighting for.”

It’s a fight that proceeds with more yeshiva doors swinging open.

In the coming months the state education commissioner is expected to release new guidelines for measuring the progress of yeshivas.