ST. LOUIS — With heroin becoming cheaper than a six-pack and as easy to obtain as pot, police and prosecutors are turning to more aggressive tactics against the drug, dusting off little-used laws to seek murder charges against suspected dealers and provide for longer prison sentences. Angry suburban parents are joining the effort, too. They’ve organized anti-drug rallies and founded organizations to spread the word about heroin in affluent areas where it is usually considered a distant, unlikely threat.

The more assertive approach is not entirely new to the drug war, but it’s being adopted more widely and in more areas that have rarely been so bold — comfortable residential communities.

“We are going to treat every overdose scene like a crime scene. We are going to treat every overdose as a potential homicide,” said Stephen Wigginton, U.S. attorney for southern Illinois. “Heroin is the bullet.”

Mexican cartels a half-decade ago created a form of the drug so pure it can be snorted or swallowed instead of injected, making heroin more appealing to teenagers and suburbanites who don’t want the stigma of shooting up.

The extreme purity — often 50 percent or higher — means today’s heroin is far deadlier than in the past. As a result, heroin deaths have spiked over the past few years in some parts of the country.

Few places have been as devastated as the St. Louis area, where the city and county reported 116 heroin deaths in 2010 and 194 last year. The increase was even more pronounced across the Mississippi River in Illinois’ Madison County, where the death toll has climbed from just five in 2008 to 26 last year.

Part of the problem is availability.

“Heroin is easier to get than marijuana now,” said Jim Shroba, the Drug Enforcement Administration agent in charge of the St. Louis office.

It’s also cheap: A “button” of heroin — enough for one person to get high — can cost as little as $6.

In the St. Louis suburb of Troy, Ill., young Shannon Gaddis finished off a snow day last year by snorting heroin. The overdose killed her.

The death of the animal-loving high school cheerleader “put this issue sharply into focus,” said Madison County State’s Attorney Tom Gibbons.

About a year ago, St. Louis County police began warning of the drug’s risks at heroin town hall forums, which were held in small meeting rooms. The response was so great that the gatherings now fill high school auditoriums. Similar meetings are being conducted throughout the region. Authorities are also redoubling their efforts to get users into rehab. St. Louis County officers now provide a small card to everyone arrested for heroin with a 24-hour phone help number on one side and police contacts on the other — in case they want to turn in their dealer.