The online comment at the end of the Bangor Daily News’ story announcing the expiration of Ayla Reynold’s search reward money reads: Poor Ayla :(

Even a $30,000 incentive couldn’t prompt discovery or recovery of the Waterville toddler.

Police don’t expect to find Ayla alive, and the reward money expired June 30. But disappointments cannot and will not stop the work that must continue in order to reveal what happened to her. Many cases take time. Justice can take time.

And while crime tip rewards can sometimes be useful in persuading people not directly involved with a case to come forward, they are by no means a crime-solving tool to rely on. The reality is that most reward money goes unclaimed.

Though the reward didn’t generate substantial leads about what happened to Ayla, who was 20 months old when she was reported missing by her father, Justin DiPietro, on Dec. 17, it changes nothing about police officers’ commitment to the active investigation.

“It doesn’t change our efforts,” said Lt. Christopher Coleman, head of the Maine State Police’s Major Crimes Unit for the northern part of the state.

It’s difficult to get reliable statistics about the success rate of rewards because there are many different variables. Rewards are often offered over various periods of time and for different types of crimes — some more difficult to solve than others. But it’s clear their success is the exception, not the norm.

For example, the chamber of commerce in Savannah, Ga., established a crime reporting program in 1983 and offered monetary rewards for good tips. Over its first 10 years of operation, the program handled 200 calls per month. Ten percent of the calls contributed to the arrest of a suspect, the recovery of stolen property or the seizure of illegal drugs or contraband, according to the National Crime Prevention Council.

Other cities have kept records, too. In 1993, the Los Angeles City Council paid out 10 of a total of 73 rewards, according to the LA Times.

In 2010, Pennsylvania Crime Stoppers, which offers cash rewards, advertised 92 unsolved crimes, and the resulting tips yielded eight arrests. In 2011, the organization advertised 61 unsolved cases and made four arrests.

Reward money isn’t always reliable, but it certainly can’t hurt. In Ayla’s case, the money was put up by attorney John Nale and a group of local businesses and individuals. At the very least, their offer helped keep Ayla in the public eye. Her case has spurred one of the largest missing persons searches in Maine history and generated national attention.

Police say the three adults in DiPietro’s home the night before Ayla was reported missing — DiPietro, his sister and his girlfriend — have not been forthcoming with details about her disappearance. But they have not said they are suspects.

So Ayla’s case continues. Even though her family sadly should not expect Ayla’s return, hope remains that the person or people responsible will one day receive the appropriate punishment. If money doesn’t entice the truth, maybe time will.