Investigators say it was a tip about frequent bus trips from Texas to Sun Prairie that caused suspicion.
Police and Dane County officers investigated and arrested three people in what they say is the biggest drug bust in Sun Prairie in 30 years.
Two of the suspects were arrested after getting off the bus last Friday in Sun Prairie. The third person was arrested at the bus stop.
Police say 63 pounds of marijuana worth about $176,000 was found in the suspects' luggage.
The couple from Laredo, Texas and a Madison man are being held in the Dane County Jail.