About Us

DNA Drug Screening Services is a national company that was founded in San Jose, California in 1989 and is owned by Colleen Wienhoff, a nationally recognized expert in drug testing with over 25 years in the industry.  Our dedicated staff of friendly professionals is always eager to help our clients.

Of primary focus to us is DOT compliance.  Our knowledge of and strict adherence to DOT standards in administering testing programs has situated us as industry leaders and experts.

With over 3000 client companies, DNA Drug Screening Services is California’s most trusted drug testing program administrator.  Our clients include large and small municipalities, State agencies and private companies from all industries.

Our parent company is Wienhoff Drug Testing of Boise, Idaho; our sister company is Bio-Med Testing Services, Inc. of Salem, Oregon.

Colleen Wienhoff - owner of Wienhoff Drug Testing (Boise), Bio-Med Testing Services, Inc. (Salem), and DNA & Drug Screening Services (San Jose)

Colleen Wienhoff – owner of Wienhoff Drug Testing (Boise), Bio-Med Testing Services, Inc. (Salem), and DNA & Drug Screening Services (San Jose)

Colleen Wienhoff – Owner of DNA Drug Screening Services

“Sometimes employers get upset at us when one of their employees tests positive, yet we are not the ones who made the choice to use drugs.”
  -  Colleen Wienhoff - Owner

Colleen is compliance-driven, knowledgeable and has a deep desire to help clients avoid problems caused by drug and alcohol abuse. Colleen is well educated in her field:

  • Breath Alcohol Technician (BAT) Master Trainer
  • Certified Professional Collector (CPC)
  • CPR – First Aid Instructor Trainer
  • Designated Employer Representative (DER) Trainer
  • Expert Witness for the court system

Read Colleen Wiehoff’s full Bio


Emanuel Carvalho – Site Supervisor at DNA & Drug Screening Services in San Jose

“I always try to treat people with respect and avoid being judgmental. We deal with people from a lot of different walks of life - from the homeless, to the working class, to professionals, and even the Secret Service. Our goal is to treat everyone with respect.”
  -  Emanuel Carvalho – Site Supervisor

DNA & Drug Screening Services is a collection site for many different labs, so those labs can process those collections. Between 80 to 100 people per day come in for DNA and drug tests.

Emanuel enjoys dealing with clients and making sure they have a satisfactory experience. “I enjoy my supervisory role, ensuring our employees do their job correctly and working with accounts receivable and accounts payable. I’m very interested in business and how to grow a business.” He does all data entry and makes sure the collectors do their jobs correctly. He has worked at DNA & Drug Screening Services since Colleen Wienhoff bought the business in 2010.

Emanuel has obtained the following education to help him do his job better:

  • Associate Degree of Science in Medical Assisting
  • Breath Alcohol Technician (BAT)
  • Certified Professional Collector (CPC)
  • Certification in Drug Testing Management from DATIA

Read Emanuel Carvalho’s full Bio