SAN JOSE — A downtown clothier was arrested this week after monthlong surveillance revealed he was dealing crack cocaine out of his storefront, according to the San Jose Police Department.

Adding to his troubles is a counterfeiting allegation after police suspected much of the supposed brand-name merchandise for sale was fake.

Felix Osifo, 43, was arrested Wednesday evening on suspicion of drug trafficking and counterfeiting by the police Downtown Service Unit, which specializes in monitoring night life and quality-of-life issues in the heart of the city.

The fact the man accused of dealing drugs was a merchant in the area was a surprise to unit supervisor Sgt. Mario Brasil, who has been policing downtown for several years.

“In my career, I’ve never dealt with a rightful business owner selling drugs,” he said. “We’re hoping it makes a dent in the drug scene. But we’re also realistic about how big the problem is.”

Brasil said about a month ago, a neighborhood regular tipped police to suspected drug activity involving the owner of 4-You! Clothing, on East Santa Clara Street between Seventh and Eighth streets. That sparked a monthlong investigation that entailed periodic surveillance.

Officers watched as buyers approached the front of the small shop and made drug transactions in plain view, Brasil said. They eventually gathered enough details to obtain a search warrant, and on Wednesday did some last-minute surveillance before closing time.

“In an hour, there were 10 to 15 customers who came to the doorway,” Brasil said. “This was the place to get crack in downtown. Very popular spot.”

As Osifo closed up shop, officers served the warrant and searched the store and his car, where they found 6.3 grams of unbroken crack that would yield about 20 rocks — worth upward of $500 — and over $3,600 in cash. While Osifo operated as a clothier, police believe the cash was generated mostly from crack.

“We didn’t see many clothing transactions,” Brasil said, alluding to the surveillance.

The search also revealed that much of the clothing for sale was counterfeit, and police tapped expertise from Homeland Security to examine what were believed to be imitation items including sports jerseys, purses, T-shirts and jeans.

Seeing drug activity in the area is not unusual for regular area visitors and merchants, but the arrest nevertheless came as a shock to neighboring business owner Dave Diggs, who runs a barbershop two doors down and counted himself among Osifo’s customers.

“I never would have guessed this,” Diggs said. “He seemed like a nice guy.”

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.