Understanding MPD’s 94% Homicide Closure Rate

At a press conference today at MPD headquarters, Police Chief Cathy Lanier and DC Mayor Vincent Gray both touted the city’s 94 percent homicide case closure rate for the year.

Gray called the number “astounding.”

Said Lanier, “We used to be known as the murder capital of the world and the city of unsolved homicides. Our detectives and our police officers have done an amazing job in turning that around. We are no longer either one of those things.”

But understanding where this number comes from is important: 37 of the homicides counted toward the year’s closure rate were not committed in 2011.

The calculation that MPD uses to calculate closure rate is outlined by the FBI’s Uniform Crime Report, Lanier said. It allows police departments to include closures of old cases when counting the total number of case closures for the current calendar year.

For example, 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.

According to Homicide Watch DC’s data, 61 homicides which occurred in DC this year were closed with at least one arrest. At the press conference Friday, Lanier said 37 cases older than 2011 were also closed this year.

So, 61 (cases from 2011) plus 37 (cases from previous years) equals 98 total cases closed in 2011.

Lanier said a total of 101 murders have been closed this year; it’s unclear when the additional three homicides that were closed took place. But, 101 (the number Lanier said were closed) out of 108 (the number of homicides reported in 2011) is 93.5 percent.

UCR guidelines are followed by all jurisdictions for homicide reporting,” Lanier said.

But Kristopher Baumann, the chairman of DC’s police officers’ union, said calculating case closure rate in such a manner isn’t “accurate.”

We’re doing a good job closing cases,” he said. “But closed cases from this year and closed cases from other years are two separate things.”

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