By Randy Dotinga.

Crime statistics published earlier this year disclosed that the San Diego County Sheriff’s Department has a “homicide clearance rate” of 250 percent for 2013. Yes, 250 percent for just one year.

The county’s homicide detectives may be good, but they’re not that good. As far as we know, they’re not solving cases that didn’t actually happen. And we haven’t seen evidence of “Minority Report”-style pre-crime investigations. (Er, scratch that – I guess we have.) So what’s going on?

The truth is the number is a bit off. The clearance rate isn’t 250 percent. It’s actually 240 percent. No kidding.

No one’s fudging the stats, and the Sheriff’s Department isn’t doing anything unusual. The statistics are legit, if mighty peculiar, because they track crimes and their outcomes in a weird but FBI-blessed way.

Cold Cases Boost New Numbers

The system is simple: The crime statistics list a homicide as occurring in the year it happened, but as being “cleared” in the year it was cleared. If a 2003 murder is cleared in 2013, for example, it boosts the law enforcement agency’s clearance rate for 2013, potentially pushing the annual clearance rate above 100 percent.

According to its own statistics, the Sheriff’s Department investigated 10 new homicides in 2013 but cleared a total of 24 cases that year. That makes for a 2013 clearance rate of 240 percent. (A San Diego Union-Tribune articlelisted a 250 percent solve rate for the Sheriff’s Department in 2013 based on six homicides and 15 cleared cases. A Sheriff’s Department statistician provided different numbers to VOSD.)

Weird System Could Be the Simplest Approach

Why does law enforcement track crimes this way? Charles Wellford, a criminologist and University of Maryland professor emeritus, thinks it’s the simplest approach.

“The alternative would be to follow up homicides for a much longer time but then the issue is when to stop,” he said. “A three-year window might make sense but would be harder to collect.”

It’s possible that clearance rates over 100 percent could be the product of a police department with a crack cold-case squad whose successes hide a poorer rate at solving new murders. But Wellford doesn’t think that’s very likely.

“You do not have rates above 100 percent very often,” he said. “My experience suggests that when you have rates above 100 percent you have an agency that clears homicides quite well and has a good cold case squad.”

Sheriff’s Detectives Solve Most Homicides

The Sheriff’s Department has been solving most homicides, at least recently. As of Aug. 28, the department said it had cleared 14 of 20 homicides from 2011, 20 of 26 homicides from 2012 and 14 of 20 homicides from 2014.

There are some caveats about homicide statistics. The figures don’t include killings in self-defense or fatal shootings by law enforcement officers.

And there’s one more thing: A homicide is “cleared” when the cops believe that they’ve solved the case and the culprit has been apprehended and turned over for prosecution, or is dead. This doesn’t mean detectives had the right man (or woman), or that the culprits are ever punished.

Why ‘Cleared’ Doesn’t Mean What You Think

A “cleared” case could end in an acquittal — think of the O.J. Simpson murder trial. Or it could fail to end in a successful prosecution for a variety of other reasons. An L.A. Times investigation found that of 9,400 Los Angeles County murder cases in the early 1990s, only about a third resulted in convictions on manslaughter or murder charges.

It’s also important to note that impressive-sounding clearance rates may hide the truth. Many cleared cases are what cops refer to as “self-solvers” — eminently easy cases that don’t require any keen investigative skills.

Cleared cases can include “murder-suicides, simple domestic homicides, killings witnessed by police officers, cases in which suspects were caught running from the scene, and so forth,” writes Jill Leovy, a reporter with the Los Angeles Times, writes in her 2015 book “Ghettoside: A True Story of Murder in America.”

“The prevalence of self-solvers,” she writes, “meant police agencies had to solve a few additional challenging cases to produce a natural 30 or 40 percent clearance rate in official tallies.” In L.A., some cops dismissed mediocre detectives who had trouble solving anything but the easiest cases as “forty percenters,” she writes.

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Originally posted at Voice of San Diego.