Adachi said the chain of custody refers to evidence -- in this case drug evidence and what happens to it from the time it's seized from a suspect, until the time it's submitted for trial.
Defense attorneys are now saying even if San Francisco's drugs are re-tested, they will never have credibility because the chain of custody was broken.
Rodney Williams left court on Monday heading home for a soul food celebration.
"I'm feeling good, like I'm getting out. I'm finally free," he said.
Charges of cocaine possession against the 23-year-old were thrown out.
More than 100 cases have been dismissed since last week because of accusations against a former technician in the SFPD narcotics lab.
60-year-old Deborah Madden is accused of stealing and using some of the drugs she was supposed to be testing.
According Adachi, the integrity of the evidence in countless cases is now in doubt.
"We don't know to what extent evidence was tampered with. Was evidence removed? Apparently so. Was evidence shifted from one case to another? We don't know," he said.
A routine, independent audit of San Francisco's lab last November criticized it for poor record keeping in tracking drug evidence.
Adachi is now asking the district attorney for a list of cases dating all the way back to January 2000.
"We want to see every case in which Ms. Madden, the technician, was a witness. We have trials in which she testified as an expert witness," Adachi said.
It's not clear how far back the district attorney is willing to go, but an investigation is certainly underway.
"I believe there is a robust and healthy review occurring in terms of what happened looking back and what we need to do going forward in terms of accountability for people who are committing drug crimes," San Francisco District Attorney Kamala Harris said.
San Francisco is now sending confiscated drugs to outside labs for testing, including one in San Mateo. But defense attorney Peter Fitzpatrick says that won't solve the problem.
"Still they touched the evidence they are sending out, so it all went through the contaminated lab. How do you fix that? You can never fix that," he said.
SFPD Chief George Gascon says he found out about the situation in February, though Madden's sister tipped off authorities two months earlier.
"This investigation will proceed. I've told the media and the public that we'll get to the bottom of this," he said.
There are two audits of the drug lab underway including one by the state attorney general and on Monday, the president of San Francisco's Board of Supervisors, David Chui, offered to submit legislation mandating safeguards if law enforcement feels that's needed.