A police dragnet Monday was seeking the supplier of a deadly heroin laced with a powerful tranquilizer that killed 12 people over the weekend.

Police in Connecticut, New York and New Jersey on Sunday cruised drug-plagued neighborhoods to warn heroin addicts by loudspeaker to avoid "Tango and Cash" - the brand name marked on packages of the lethal narcotic.They told people to seek medical help immediately if they had taken the drug, but as word of the danger spread, police said at least one dealer simply changed the name and continued to sell it.