How many 2007 homicides were solved?

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An arrest was made in about 41% of all murders committed in Los Angeles County in 2007, according to data collected by the Homicide Report.

The total rises to about 46% when only cases from the first six months of 2007 are considered; presumably, some homicides from the second half of the year may need only weeks or months of further investigation to be resolved.

The HR analysis shows that there was virtually no difference in success rates overall in 2007 between the Los Angeles Police Department and the Los Angeles County Sheriff’s Department.

Although these two agencies--both among the largest in the country--follow very different models in investigating homicides, both agencies had arrested suspects in about 40% of all homicide cases by year’s end. The finding suggests that the problems involved in catching and jailing killers may be bigger than the police. Community attitudes and behaviors and prosecutors’ thresholds for filing homicide charges may have more to do with whether murderers end up behind bars than any particular law-enforcement model.

The data also showed that solve rates varied across geographic and demographic lines.

For example, detectives in the three highest-homicide precincts of the Los Angeles Police Department in South Los Angeles had arrested suspects in 38% of cases from the first six months of 2007, a significantly lower rate than in the county overall. This is consistent with past years’ trends and is a reflection, at least in part, of the greater difficulty of solving cases in high-crime environments where many people are afraid of testifying against gang members in court, and detective caseloads are higher.

Detectives in LAPD’s Southwest Division, for example, a high-homicide precinct covering the Exposition Park and Jefferson Park areas, had 75% higher caseloads than detectives in LAPD’s West Los Angeles and Devonshire divisions in 2007. Southwest detectives handled an average of more than 10 cases per detective pair in 2007; West L.A. and Devonshire detectives handled the equivalent of about six cases per pair.

Sheriff’s homicide detectives also carried relatively high caseloads in 2007—at least nine homicide cases per detective pair, not including the injury-only police shootings those detectives also investigate.

The rate of arresting suspects was lowest for cases in which black people were victims. Countywide, suspects had been arrested in 38% of cases in which blacks were victims, versus 42% for Latinos and 54% for whites.

There are many different ways to calculate solve rates, or clearance rates, for homicide. While this analysis considers only homicide cases resolved by an arrest, an additional portion of cases involve investigations that are concluded without an arrest, usually because there was some impediment to prosecuting a known suspect.

If these so-called “cleared other” cases are considered together with those resolved by arrests, the countywide solve rate for 2007 rises to about 45%, and 49% if only the first six months of 2007 are considered.

The majority of “cleared other” cases in 2007 involved homicides in which prosecutors declined to file charges due to concerns that circumstances of the crime were clouded by self-defense issues.

All of these findings are preliminary, since an undetermined number of cases will be solved in coming months or years. In fact, this analysis probably says more about the pace of justice than long-term outcomes: Many homicide detectives suggest a minimum of two years is needed to fully investigate homicide cases.

Also, the finding may not provide a good measure of performance by homicide-investigating units. Because only a single year—2007—was considered, the analysis does not yield an accurate reflection of detectives’ workloads nor of their success rates, since they may be solving cases from past years even as new ones come in.

Although different in methodology, the analysis of 2007 data collected by the Times echoes previous findings on solve rates.

A 2003 Times analysis of 11,000 homicides in the city of Los Angeles between 1988 and 2002, for example, found that roughly half remained unsolved. A disproportionate number of these cases were in South Los Angeles.

Similarly, an earlier Times analysis of 9,442 homicides committed during the peak homicide years of 1990-1994 also found that only about half of these cases had resulted in arrests and charges several years later.

That study also found that only a third of these cases had concluded with anyone being convicted, and that homicides were less likely to be solved when blacks and Latinos were victims.

The Homicide Report analysis considered 710 cases in 2007, a portion of the more than 900 homicide deaths that occurred countywide in 2007. Most, but not all, jurisdictions in the county were included in the survey. Pomona, and jurisdictions handling very few homicides, were omitted because of time constraints.

Murder-suicides and cases in which suspects committed suicide before they could be arrested were eliminated from consideration. Double and triple homicides were counted as single cases. Cases in which the suspect remained outstanding on a warrant--a very small percentage of the total--were counted as “solved” on the theory that they represent well-advanced investigations. The federal government, however, does not consider such cases as solved or “cleared.”

The Homicide Report’s analysis was done by interviewing detectives or detectives’ supervisors involved in each of the 710 cases considered as of January, 2008, to determine the outcome of each case individually. Caseloads were calculated by measuring the number of working detectives against agency homicide tallies.

-- By Jill Leovy and Doug Smith/Times staff writers

(Above, unsolved cases stacked on shelves at the sheriff’s homicide bureau. Below, LAPD Southeast detectives at a murder scene last August. They solved it.)