New York ? The city medical examiner’s office says it has exhausted all efforts to identify the remains of those killed at the World Trade Center, confirming the heartbreaking truth for the many Sept. 11 families who wanted something, anything, to bury.

In the 3 1/2 years since the attack, forensic scientists have identified the remains of nearly 1,600 of the dead. But the families are now being told that the limits of DNA technology have been reached, leaving more than 1,100 of the victims unidentified.

For many of the families, any hope that their loved ones’ remains might be found had all but slipped away long ago.

They buried caskets with photographs and mementos instead of bodies. On holidays, they visit gravestones that mark nothing but a spot in the earth. For many, the trade center site in lower Manhattan, instead of a cemetery, is where they feel a connection to their loved ones.

A year after the attack, Ronald Fazio’s family held a wake with a coffin full of keepsakes, knowing his remains might never be found but needing the ritual to move on. Photos of the family dog, sand from the Jersey shore and Fazio’s favorite treat, Reese’s Peanut Butter Cups, were buried in a cemetery near their New Jersey home.

A mangled credit card was the only trace of Ronald Fazio recovered in the more than 1.5 million tons of trade center rubble that rescue workers excavated for more than nine months. Out of nearly 2,800 victims, fewer than 300 whole bodies were recovered.

Forensic teams worked around the clock after the disaster to identify the dead via DNA from toothbrushes and combs supplied by the victims’ families. During the monumental effort, the remains were kept in refrigerated trucks outside the coroner’s office.

Nearly 20,000 pieces of bodies were found in the ruins — more than 6,000 small enough to fit in five-inch test tubes. The most matched to one person exceeded 200. More than 800 victims were identified by DNA alone.

Nearly 10,000 unidentified parts have been freeze-dried and vacuum-sealed for preservation in case advances in forensic technology someday enable scientists to identify the remains.

In many cases, the fierce fires, the crushing debris and other factors prevented scientists from extracting usable DNA.

“I feel very gratified that we got as far as we did, given the quality of the DNA that we had to work with,” said Robert Shaler, director of forensic biology. “We know there’s still some DNA there in some of these remains … but we need other techniques to get at it, and when that happens we’ll have someone on the job to look for new identifications.”