Police in New Mexico say a 15-year-old boy, charged with killing his entire family, was secretly practicing his murder spree on video games.

Nehemiah Griego is charged with shooting his parents and three younger siblings to death in their rural New Mexico home this past weekend.

Investigators say the boy admitted he had anger issues and snuck out to play the games before donning camouflage for the deadly attack.

The revelation adds fuel to the debate about the impact of violent video games on young people and comes at a time when the U.S. government is pushing for more studies about what the impact violent games have on young minds.

One local psychologist says the correlation between violent games and violent behaviour is worth investigating.

"We don't know the direction of the relationship.  We do know that violent video game play is associated with some of these negative outcomes but we don't know if the negative outcomes were there first and the violent video game play was an expression of those problems,” says Ulric Wong, a clinical psychologist with the University of Calgary.  “We still have a fair bit of work to be done in that regard."

Ulric Wong is part of a team studying violent video games and the possibility violent games decrease a child’s ability to empathize with others.

Participants in the study are asked a series of questions about their exposure to video games including the amount of time they spend playing video games and what types of games they play.  Following the questions, the subjects are shown pictures of faces with different expressions and are asked to determine what emotion is being displayed.

"So far, what we do notice is people who play at least two hours of video games per day on average do rate faces less accurately," says Wong.

Wong says people who empathize less could be prone to more violent behaviours but more research is required to reach a conclusion about the influence violent video games have on real life violence.

A recent study done by a team at Brock University in St. Catharines, Ontario has found that teens that play violent video games over a number of years do become more aggressive towards other people.