The Justice Department under the Biden administration opened an investigation into Representative Ilhan Omar, Democrat of Minnesota, in 2024 to scrutinize her finances, campaign spending and interactions with a foreign citizen, according to people with knowledge of the matter. The inquiry, initiated by the U.S. attorney’s office in Washington and the department’s public integrity unit in June of that year, appears to have stalled for lack of evidence, according to one of the people who requested anonymity to discuss internal department matters. The investigation appeared to be thrust into the public spotlight on Monday, when President Trump blindsided department officials...