There's no law against driving around with a wad of cash in your car's trunk — or is there?

Prosecutors believe a Sebastopol man had just completed a marijuana deal when CHP officers pulled him over last year on a rural Santa Rosa road and found $47,000 stashed in his trunk.

There was no burning joint in the ashtray or bag of weed in the glove box, but William David Bush's black Mercedes was filled with the unmistakable odor of drying pot that caught the attention of a drug-sniffing dog, police said.

"Obviously, it was just removed from the vehicle," Santa Rosa K-9 Officer Patrick Gillette testified Wednesday at Bush's trial.

Bush was later charged with suspicion of possessing proceeds from the sale of a controlled substance, a felony carrying a possible prison sentence.

Some courthouse watchers said the case is a sign of law enforcement overreach in which police seemed all too willing to step on individual rights. But others said it is yet another example of Sonoma County's lucrative and sometime violent pot trade. The trial played out a day after deputies arrested five people in a suspected heist at an east Santa Rosa pot farm. Law enforcement officers said cash is a common byproduct of the illicit drug trade.

The amount of cash seized in Sonoma County over the past year was not immediately available.

"This kind of case is becoming more common," Santa Rosa criminal defense lawyer Stephen Turer said. "In many cases they don't find any drugs. It's just cash."

Bush's troubles started the morning of Oct. 6, 2012, as he drove along Bennett Valley Road. A CHP officer pulled him over after observing what she said was a traffic violation.

After detecting what smelled like processed marijuana, the officer searched Bush's trunk and found 10 stacks of cash sealed in plastic "food saver" bags, tucked in the leg of a pair of pants inside a suitcase.

The money itself — $46,959 in ones, five, 10s and 20s — had picked up the scent of pot and officers later found tiny particles of weed mixed with other debris on the floorboard of the car.

It appeared that Bush had recently been transporting a quantity of marijuana in the car, the officers said.

"It was very strong," Gillette testified.

Officers found other evidence consistent with cultivation and sales, they said.

A hand-written ledger on the front seat described what they interpreted to be various strains of weed, testified Sheriff's Det. Bryan Londo.

There were stubs for money-grams — a popular form of payment for low-profile growers — as well as receipts for cash purchases such as privacy fencing and fertilizer, he said.

A review of Bush's bank records showed $113,000 in cash deposits for a two-year period ending in October, Londo said.

He told prosecutor Sharmalee Rajakumaran that none of the deposits were from payroll checks.

Asked where he thought the $47,000 came from, Londo said the odor, notes and debris, as well as the cash itself, all point to marijuana sales.

"It's not just one thing," he said.

Bush, who represented himself at trial, gave police several explanations for the cash, officers said. He said it was from an ATM business he operates in Mexico but also that his mother gave it to him and that it was his life savings, an officer testified.

"He said he likes to keep it safe by keeping it in the trunk of his vehicle," Londo said in court.

The jury was expected to begin deliberations Thursday.

You can reach Staff Writer Paul Payne at 568-5312 or paul.payne@pressdemocrat.com.