For decades after he was shot and left for dead on the side of the Capital Beltway in Prince George’s County, John Nucci, a paraplegic, lived a productive life. He started a temp agency for restaurant workers. He opened his own restaurant in Leonardtown.

But when Nucci, 50, died earlier this year at Washington Hospital Center, the D.C. Medical Examiner’s Office determined complications from gunshot wounds were the to blame. The man brutally attacked in 1989 became Prince George’s County’s 12th homicide victim of 2012.

Counting homicides is serious and sensitive business for police agencies in the D.C. region. Though crimes like break-ins and car thefts are more likely to touch the lives of the average residents, murders have become a sort of measuring stick for police chiefs and their departments. Keep the count low and the closure rate high, and politicians community activists and journalists will rate you well. Oversee a spike in slayings, and you’ll face tough questions.

The fact is, though, counting murders is more complicated than meets the eye, and the murder counts and closure rates that police are required to report do not paint a perfect picture of crime in an area.

Take Nucci’s case.

On Jan. 28, 1989, Nucci and a woman he was dating were walking to a parking lot in D.C. when two men approached. One of them, according to police and news accounts, put a gun to Nucci’s head and demanded a ride.

The men sexually assaulted Nucci’s companion while the young chef drove, though they eventually let the woman out, according to news accounts and police. When Nucci himself tried to get away — apparently after refusing to take the men to his family’s home in Silver Spring — one of the men shot him and left him for dead on the side of the Capital Beltway, near New Hampshire Avenue, according to news accounts and police. He eventually crawled to the road, and a passerby found him and called for help, according to news accounts and police.

Nucci’s attackers were long ago arrested and convicted on robbery and kidnapping charges in connection with a series of similar attacks in D.C. and Prince George’s, said Capt. Joe Hoffman, a homicide commander with the Prince George’s County police department. He said both men — Kelvin Smith and Irving Brockman — were given sentences spanning several decades, effectively amounting to life behind bars. News accounts from the time say Smith received more than two centuries in prison; Hoffman said records indicate Brockman is scheduled for release in 2069, when he would be 97 or 98 years old.

So why, for statistical purposes, is the case a homicide this year?

Prince George’s and most major police departments around the country use the FBI’s Uniform Crime Reporting, or UCR, guidelines to determine how they count crime. If a person is attacked in one year and dies in another, the homicide counts in the year the person dies. The same is true if a body is found in one year, even if the victim was killed in an earlier year. It’s the only way, officials say, to prevent constantly evolving homicide totals from years gone by.

“There has to be a standard across the country, or people are going to be all over the place,” said Prince George’s Police Chief Mark Magaw. “No system is perfect.”

Homicide detectives encounter these so-called “prior year assaults” turned murders a few times a year; Prince George’s has had 12 since 2005. But no one could recall a prior year assault case that was more than two decades old. The UCR guidelines don’t have a statute of limitations, so to speak, on when an assault can no longer turn into a murder, officials said. That determination is made essentially by the medical examiner, who rules on a cause and manner of death.

All these cases, though, muddle the true picture of homicides in a given year. So far this year, Prince George’s stands at 13 homicides, including Nucci’s case and that of Alexandria activist Lenny Harris, whose body was found in a well this year, months after he was slain. The department had 26 homicides at the same time last year, not including a case that occurred in March but was not immediately ruled a homicide.

Throw in the percentage of closed cases, and the math gets even more complicated. By UCR standards, Prince George’s County police have a so-called 77 percent “closure rate.” But that figure — because of FBI standards — rewards police with closures for three homicides that were counted as murders in prior years and solved this year. In reality, police have only closed seven of this year’s 13 murders, a “year-specific closure rate” of 54 percent.

Magaw said that at community meetings and other public forums, he tries to lay out all the numbers and their complications.

“You have to be methodical and break it down,” Magaw said. “We have to count the numbers by UCR standards, which we do, and we have to explain it to the community.”

In Nucci’s case, prosecutors determined they could not prosecute Smith and Brockman on murder charges for both practical and legal reasons, Hoffman, the homicide commander, said. At the time Nucci was attacked, there was a statute saying he would have had to die within a year and a day for murder charges to be pursued, Hoffman said. Also, it made little practical sense to prosecute two men who are already effectively spending their life behind bars, he said.

At the very least, though, police officials got to count the case as “closed” by UCR standards. And it made for some interesting talk among the department’s stat nerds.

“This conversation,” Magaw said, “we have almost daily.”