Over the past year, we’ve published dozens of stories about murder in Southern California.

These stories followed months of research in which reporters for the Los Angeles News Group queried law enforcement agencies throughout the Southland on the number of homicides in their jurisdictions between Jan. 1, 2000, and Dec. 31, 2010, and, more importantly, how many of those cases remained open in January.

There were 11,244 homicides in Los Angeles County in the 11 years we researched, and we were able to obtain information on 10,501 of them. As of January, 4,862 — or 46.3 percent — of those cases remained unsolved.

• Database: Los Angeles County’s Unsolved Homicides

If those are not unsettling numbers — if they are not downright staggering — they should be.

Nearly half the homicides in the county were not solved.

Over the course of the past year, at least five arrests have been made in these cases. That number is too small to make a major statistical difference, but it is nevertheless a huge number, because in each of these cases, a life was lost.

And lives matter.

All lives.

In our reporting, we’ve told the stories of crimes, of grief-stricken families, of determined detectives and of communities grappling with challenges that all too often seem insurmountable.

• More Coverage: Getting Away With Murder

The challenges are not insurmountable, though, as can be seen in today’s story.

We may never be able to completely eradicate crime in our communities, but we can make a difference through sustained, thoughtful effort and the collaboration of local, state and national law enforcement agencies.

We must be steady and determined.

Consider the following from retired Santa Ana Police Chief Paul Walters, whose department dramatically reduced homicides during his 25 years as chief:

“I wanted to make sure I was very adamant and very outspoken about it that we’re going to go to the ends of the earth to bring people to justice,” Walters said. “So the bad guys know we’re not giving in, we’re not backing down, we’re going to do everything in our power within the limits of the law.”

It is not, however, exclusively an enforcement issue. The commitment has to come from government, as well, and from the people. We have to be committed. We have to step up.

Frank Pine is executive editor of the Los Angeles News Group.