DETROIT -

A fire investigator warns setting fires in the city of Detroit costs everyone, not just the people directly affected by the blaze.

Michael Roarty, a senior fire investigator with Rehmann, worries about what can happen around Angels' Night.

"God bless the volunteers that are certainly out there that are watching out for these abandoned structures, however they can't watch every single abandoned structure that is out there," said Roarty.  

For Roarty, Angels' Night and other fires around Halloween is a reminder of a big problem in the city.

"A lot of people that are leaving the city of Detroit. They are abandoning their houses or they are letting them go or there is a lot of foreclosed properties that are open and subject to trespass. With that what happens is you get a group of gangs or you get young children or you even get sometimes the homeowners that go into the homes and they are pouring ignitable liquid through the house and they'll set the house on fire."

Roarty said arsons can have a huge impact beyond the damage to the property.

"When the house catches fire it takes away from the resources of the Detroit fire department, who has to come out and extinguish the fire, then at the same time if the fire spreads it could spread to a neighboring home and actually destroy that home," said Roarty.

He said there were 5,770 suspicious fires in Detroit in 2011, about 94 happened during Angels' Night.

"Right now, Detroit police and Detroit firefighters are overworked and over taxed and underpaid.  And I don't want to get into the political aspects of this, but the point of it is, is somebody is going to get killed," said Roarty.

The Detroit Fire Department lost one of its own in 2008.  Walter Harris was killed while trying to put out a fire in an abandoned home.  The fire was intentionally set.

According to the Michigan Arson Prevention Committee, arsons across Michigan caused 67 deaths and 131 injuries in 2011.

People who live and work in the city worry about what could happen despite the patrols of volunteers and emergency crews on Angels' Night.

Rasheida Parker fears the vacant burned out home next to hers to be set on fire.

"I have three small children of my own and I would definitely hate for this house to catch on fire and catch my house on fire," said Rasheida Parker.    

Brenda Quintero helps run a homeless shelter in a Detroit neighborhood.  She said the shelter is taking precautions in case something happens.

"We watered down the building, we have our hose prepared and ready, definitely we have the lights, extra lighting on," said Quintero.

Roarty said Detroiters can help by being good witnesses if they see something suspicious.

"They can get a license plate number they can get a description of the individual, they can see just exactly how quickly the fire progressed and report all that information to authorities," said Roarty.

The Michigan Arson Prevention Committee said arsons and suspicious fires cost Michigan residents more than $166 million last year.  Roarty said that doesn't include indirect costs like medical care, temporary shelter, business interruption, fire investigation and prosecuting those responsible.

He also said there is another cost t all of us.

"You wonder why your insurance rates are so high in the state of Michigan, it's because of higher rates of fraud and  arson that occur within the state of Michigan," said Roarty.

The Michigan Arson Prevention Committee offers up to a $5,000 reward for information that leads to an arrest or conviction.
last year those tips led to 28 arrests.

You can call 800-44-ARSON, for more information how to report an arson, click here.