The Norfolk District Attorney‘s Office will offer “substantial grants’’ for evidence audits to any police department in Norfolk County, after an audit of Braintree’s evidence room revealed the disappearance of guns, drugs, and hundreds of thousands of dollars.

District Attorney Michael W. Morrissey also announced Thursday that his office would offer evidence training to any department that requests it.

“The District Attorney and his staff recognize that these are the early days of what will be a long process,’’ Morrissey’s office said in the statement announcing the grants and training.

Four low-level criminal drug cases were dropped Thursday because of tainted or missing evidence from the Braintree evidence room, officials said, and prosecutors are contacting hundreds of defense attorneys who have had Braintree clients in the past several years.

The audit in Braintree, undertaken in the spring and released Wednesday night, showed that thousands of pieces of drug evidence, 60 or 70 guns, and more than $400,000 had vanished since 1999.

Braintree Police Officer Susan Zopatti, who ran the evidence room starting in 2013, killed herself in May after the auditor spoke with her for the first time. Police have recovered all but 12 of the guns, officials said, and about $140,000 of the cash.

Town officials have said much of the missing evidence was probably disposed of during “purges’’ in 2009 and 2012 but never properly deleted from computers. However, much evidence vanished after 2012, according to the audit, which discovered bags of drugs and money torn open and emptied out.

The town has asked the attorney general’s office to help investigate the situation.

Prosecutors have reached out to about 200 defense attorneys so far to tell them of the evidentiary problems. So far, at least 10 cases have been dropped by prosecutors because of the issues with the evidence room.

Evan Allen can be reached at evan.allen@globe.com. Follow her on Twitter @evanmallen.