Watch the full one-hour special — “'A Necessary Evil’: The Cost of Confidential Informants” — below. You'll also find more reporting and web extras on the use of confidential informants.

KSAT 12 Investigative Reporter Tim Gerber reveals a string of wrongful convictions here in Bexar County, confronts those responsible, and also shows you how the problem might be stopped.

Get updates on this and other Defenders investigations straight to your inbox.