House Democrats Demand Answers After ProPublica Probe on U.S. Citizens Detained by Immigration Agents

1. What happened

   According to ProPublica, House Democrats have demanded answers following its investigation into U.S. citizens detained by immigration agents. The specific findings and the lawmakers' requests are not included in the material provided.

2. When it started

   The publication date and timing of the congressional demands are not given in the material provided.

3. How it spread

   The story is based on a ProPublica investigation, as its headline indicates. The reporting methods and sources are not described in the material provided.

4. Why it matters

   The Democrats' demands follow the ProPublica reporting. Their stated reasons and any responses from immigration authorities are not included in the material provided.