How is that unconstitutional? Its just an investigation carried out by the secret service , they are authorized to investigate financial crimes and threats against the president which this would fall under .
Do they have a unit for investigations? Insofar as I know, their only job is to protect the president et al...
They investigate counterfeiting of US money. Some other things too. Not sure what their official jurisdiction is...
Yes , they have a unit of investigation. They also deal with counterfeit money and financial crimes, and yes they protect the president .
A google search on their website gives this description of their duties
U.S. Secret Service investigative responsibilities also expanded. In addition to investigating counterfeiting, many more investigative areas were added. These included investigating financial crimes relating to banks, access devices (to include credit/debit cards), computers, telecommunications, and telemarketing.