A new study of youth crime shows teens are most likely to commit offences on a weekday, during and after school hours.

The study is based on interviews with 123 young offenders in Calgary -- the first phase of a three year study.

Researchers also looked at data from the Calgary Police Service Police Information Management System.

"The data demonstrate that more youth offending occurs during the week, and during school or after school -- not on the weekends or in the evenings as might be expected," says the study.

Lead researcher Leslie MacRae, of the Canadian Research Institute for Law and the Family, told CTV Calgary that youths were mostly committing crimes between 9 a.m. and 6 p.m.

"That was something that was really quite surprising to us," she said.

The study suggests that a "lack of investment in school (i.e., skipping, dropping out) and participation in after-school activities" may be behind the findings.

"We have an extensive amount of programs that we already have in place, this tells us now that we should refocus, reemphasize those programs or we should expand those programs," Calgary Police Inspector Bob Couture said Monday.

Most of the 123 young offenders profiled come from troubled homes, where parents are often absent and family violence is common.

Almost all of the kids profiled admitted to using drugs.

Calgary Community & Neighbourhood Services' Chris Branch said Tuesday that the study is a real message to parents and to the community that something needs to be done during those critical hours.

Branch also said early intervention is an effective way to help youth avoid the criminal lifestyle.

"Some of this really negative criminal behaviour peaks at about age 14," said Branch. "You really need to intervene prior to that, you need to get working with kids prior to the age of 12."

The study will continue to follow the young offenders for two more years with results released annually.

Researchers are hoping to develop a model for predicting why some youth become more seriously involved in offending than others.