The Post releases a report today on the extremely high homicide case closure numbers being posted by MPD. Under Chief Cathy Lanier, the department says it’s reached a 94 percent closure rate—far higher than the 65 percent national average—but the Post says the calculations don’t show a true picture.

But an examination of District homicides found that the department’s closure rate is a statistical mishmash that makes things seem much better than they are. The District had 108 homicides last year, police records show. A 94 percent closure rate would mean that detectives solved 102 of them. But only 62 were solved as of year’s end, for a true closure rate of 57 percent, according to records reviewed by The Post.

D.C. police achieved the high closure rate last year by including about 40 cases from other years that were closed in 2011.

The cases date from 1989, records show. The pattern was first reported by a local Web site, homicidewatch.org, in December.

As Homicide Watch D.C. wrote at the time, under the math MPD is using, “If 10 homicides were to occur in 2012, and a police department made arrests in five of those cases, but also closed five homicides that occurred in 2011, the case closure rate for 2012 would be 100 percent.”

Which, obviously, is a problem. But one that’s not exactly a surprise. And it reminds me of an episode of This American Life where a New York City cop exposes the funny counting going on in his precinct. The police in that case were frighteningly corrupt, but one detail is especially relevant to the MPD homicide closure rate: The political system incentivizes police to make themselves look ever more effective, which is how you get to ridiculously high numbers like 94 percent.

Photo by Darrow Montgomery