Police say more people are growing marijuana inside their homes than ever before.

Some have large scale operations, capable of producing thousands of dollars worth of illegal drugs, and it could be happening in the house next door.

Police photographs show an upswing in the amount of indoor marijuana growing operations in mid-Missouri over the past year. KRCG concealed the identity of an undercover Columbia police officer, who recently finished special training on how to investigate pot houses.

“It is hard to find these indoor marijuana growing operations without the help of people noticing unusual behavior in their neighborhoods,” said the undercover officer. “People need to look for things like covered windows and very little activity in an apartment building. That usually means someone is using the apartment to grow pot."

Police say most growing operations are found at rental properties. After neighbors complained of suspicious activity in a south Columbia duplex, the sheriff's department checked the power bill. It revealed the duplex was using as much electricity in just two days as the average family would in a month. Once inside, they found the duplex had been renovated with new wiring, grow lamps, water and ventilation systems.

"They had special irrigation techniques that they employed,” said Det. Tom O’Sullivan with the Boone County Sheriff’s Department. “They were quite creative with the way modified this duplex."

But police say the grow houses are not just in rental properties. Another case in Columbia busted attorney Anthony Phillips and his neighbor Steven Maurer. They were arrested in March for growing nearly 500 marijuana plants inside their homes in the Vanderveen subdivision. Police say the homes' basements had false walls and special modifications keeping the operation undetected for years.

Jefferson City is seeing the problem, too. Just last month, police raided two homes that were getting ready to grow pot. Inside, thousands of dollars of sophisticated equipment had been installed.

Police say you can help by going by the old saying, if something doesn't look right, it probably isn't right. That's when you should call the police if you suspect someone is using their home to grow marijuana.

“We rely quite a bit on citizens reporting suspicious activity,” said Det. O’Sullivan. “We're always appreciative of that. We encourage people to be aware of what's going on in their neighborhood."

High power usage is a key sign of growing marijuana because of the use of grow lamps, but most utility companies do not monitor individual usage to check for abnormalities. That's why authorities need your help to report suspicious activity.

While indoor marijuana growing operations are on the rise, police say meth is still the number one drug being manufactured in mid-Missouri.