SAN DIEGO -- A Tierrasanta mother is trying to figure out how she'll pay an expensive bill for her son's behavior during his father's deployment.

Last January, San Diego's bomb squad was called to Farb Middle School in Tierrasanta for a suspicious-looking device. Denise Johnson said the device was a fire extinguisher her 15-year-old son innocently left hanging on a chain-link fence. Police said it could have been a bomb.

"I didn't believe it because I know he doesn't have to know-how to build such a thing," said Johnson.

Regardless, her son reached a plea agreement in juvenile court and is currently on probation. The judge ordered the family to pay for the emergency response and investigation, which totaled more than $11,000.

"I couldn't believe it. I was shocked," said Johnson. "The first thing I thought was, 'how are we going to eat?'"

Johnson did not want to identify her son. She said he may have been acting out because his father was deployed overseas with the U.S. Navy.

"Deployments don't have a positive impact on families," said Retired Navy Capt. Paul Steffens. He said wartime deployments have been hard on families left behind and suggested schools and authorities should take that into account when children get into trouble.

"They ought to find out whether that is caused by a deployment or not because it's definitely going to influence the behavior," said Steffens.

Johnson said San Diego's Collections Department noticed that and gave her a break.

"She said, 'well, being that Dad was gone, we're just going to lower it a little bit but you still have to pay this,'" said Johnson.

The Johnsons' bill was cut from $11,000 to $6,000. The city wouldn't comment on the Johnson's account but did say they do not have a policy giving discounts for military families. Johnson said she is working out a payment plan.

"I would just ask that the community have compassion for my family as they would their own," said Johnson.