There are so many federal agencies and agencies and departments within agencies that I could probably study it for a month and still not understand it all. If it can be done in three steps, the federal government will do it in 31 steps.
Each of the dozens of federal law enforcement agencies have different responsibilities and are under different controlling department. Departments of Justice, Homeland Security, Treasury, blah blah blah….
Many of the agencies that existed for the first 20 years of my career changed for the last 18 years due to 9-11 and a massive government shakeup. That is why Department of Homeland Security (DHS) was created, in 2003.
A federal agent is a federal agent just like in Texas a peace officer is a peace officer. It doesn’t matter whether city police, sheriff department, game warden, alcoholic beverage, college police, etc. , they are all Texas police officers. But…. like federal agencies, they are created for a specific purpose. The federal special agents are all federal law enforcement.
It is so long ago that I don’t remember but when I was doing child victim crimes about 25 years ago and before DHS, if I remember correctly some child exploitation was usually investigated by US Customer such as illicit child photographs. US Customs and INS were combined into ICE and under the supervision of the newly created DHS. So there is a chance that child photography cases went to DHS by way of ICE by way of Customs. So why did DHS raid a home? Because it was probably part of their investigation.
Crimes also overlap like the DEA does drugs and the ATF does firearms so when a guy is selling drugs to fund illegal gun sales, who takes the lead, DEA or ATF? The prosecution doesn’t matter because that is all done by the US Attorneys Office. It’s no different than the Jefferson County DA takes all criminal cases (except Class C like traffic citations) from BPD, PAPD, TPWD game wardens, Sheriff Department, etc.
The Feds raid houses just like the local police. There are just a lot more state licensed officers than federal agents.
I wouldn’t read too much into a warrant served at a home done by one federal agency rather than another.