EL PASO - One immigration agent was accused of running an Internet pornography business and enjoying an improper relationship with an informant. Another let an informant smuggle in a group of illegal immigrants. And in a third case, an agent was investigated for soliciting sex from a witness in a marriage fraud case.

These troubling misdeeds are a sampling of misconduct by federal Immigration and Customs Enforcement personnel as the agency seeks to carve out a bigger role in the deadly border war against Mexican drug gangs.

According to documents obtained by The under the Freedom of Information Act, ICE agents have blundered badly in their dealings with informants and other sources.