The phrase "abandoned a case" is correct and usable in written English.
It can be used in legal contexts or discussions about investigations when referring to the act of discontinuing or ceasing to pursue a particular case.
Example: "After months of investigation, the police decided to abandon the case due to lack of evidence."
Alternatives: "dropped a case" or "closed a case."
The government's decision to abandon a case that prosecutors had once compared to nuclear espionage shattered an uneasy calm that had settled over the Justice Department and the F.B.I. in the waning months of the Clinton presidency.
It was "disturbing," he said, to learn that a legal services lawyer must abandon a case in which the validity of a law or regulation arose and was not permitted even to answer a judge's question about whether a case raised a constitutional issue.
In 2015, a Guardian investigation revealed that police departments had to sign a non-disclosure agreement with the FBI in order to use Stingray devices which said that police must hide the program's use from defense lawyers and the public, even mandating that they abandon a case if they fear the program's use might be revealed in court.
We already knew that the FBI had successfully hacked the phone when it postponed and later abandoned a legal case against Apple to unlock the phone, but until now, it remained a mystery how it happened.
During the Obama years, they'd been routed, as Google's executive chairman, Eric Schmidt, strongly supported the president, and the Federal Trade Commission abandoned an antitrust case against the company.
In the summer of 2011, his office had abandoned a sexual-assault case against the former managing director of the International Monetary Fund, Dominique Strauss-Kahn.
The reversal comes after the government abandoned a high-profile case to force Apple to help it hack into a phone used by San Bernardino gunman Syed Farook.
In 2010, families in England and Wales had to abandon a court case when their legal aid was withdrawn three weeks before the case was due to begin.
It would be extraordinary if the FBI and/or MPD were successful in convincing a federal prosecutor to abandon a criminal case or to strike lenient plea deals with defendants in cases where a Stingray was used.
And Planned Parenthood of Kansas and Mid-Missouri questioned whether prosecutors were encouraging conspiracy theories as a way to blame abortion rights supporters while abandoning a losing case.
