School truancy and dropouts are critical public safety issues. I know from my years in and out of the courtroom that if we only focus on adult offenders, we will never effectively address the crime problem.

Additionally, addressing crime by simply locking up violators is not cost-effective. It now costs $50,000 per year to house someone in prison (more than the cost of one year's tuition at UC Berkeley).

We must do more to prevent crime. Attending school and obtaining a good education is the best deterrent to crime. The fact of the matter is that we would have far fewer criminals, and far lower levels of incarceration, if we focused more on education and eradicating truancy and dropout rates.

Truancy is a precursor to dropping out of school. According to the California Department of Education, over the course of an academic year, the truancy rate for all California public schools in 2009-10 was 28.15 percent. The truancy rate for Contra Costa County in this same year was 32.45 percent. Chronic absenteeism is not only a precursor to dropping out of school; it is the most powerful predictor of delinquent behavior.

High school dropouts are more than three times as likely to be arrested and more than eight times as likely to serve time in jail or prison.

A recent study analyzed the relationship between graduation and crime and concluded that a mere 10 percent increase in high school graduation rates in California would reduce

This would result in 500 fewer homicides and 20,000 fewer aggravated assaults each year in California, including 19 fewer murders and 479 fewer aggravated assaults in Contra Costa County.

It is estimated that the 120,000 students who drop out of school each year will collectively cost California $46 billion over their lifetimes. Each year's dropouts cost California more than $1 billion in juvenile crime costs.

Truancy is a crime, and the California Education Code and Penal Code outlines consequences both for students and their parents. I am working closely with school superintendents, school districts and parents and students to resolve attendance problems early.

I have invited all schools to call upon our office to address parents and students about truancy. The Board of Supervisors recently enacted a daytime curfew ordinance to keep minors out of public places during school hours for a public safety purpose.

When our collective efforts have failed, my office is compelled to ensure that children are in school by prosecuting parents for the truancy of their children.

The cost of children not staying in school affects all of us. It costs students an education, resulting in reduced earning capacity as they enter adulthood.

It costs school districts hundreds of thousands of dollars every year in lost federal and state funds based on attendance -- the net effect being reduction of services for everyone in school.

It also ultimately costs businesses, which must pay more to train uneducated workers. And it costs all taxpayers, who must pay higher taxes to support local law enforcement, as well as welfare costs for dropouts who end up on welfare rolls or underemployed, and it increases the crime rate and affects public safety.

As district attorney, my primary responsibility is the safety of our residents and our communities. Thus, reducing truancy, dropout rates and improving graduation rates is one of the objectives of our office.

We all have a high stake in high school graduation. As we were taught in school: "An ounce of prevention really is worth a pound of cure."

Mark Peterson is district attorney of Contra Costa County.