You can read it here; here's the opening paragraph plus another paragraph, though the indictment offers considerably more details as well (note that, as always, an indictment is just the government's allegations):
The Southern Poverty Law Center's ("SPLC") stated mission included the dismantling of white supremacy and confronting hate across the country. However, unbeknownst to donors, some of their donated money was being used to fund the leaders and organizers of racist groups, including the Ku Klux Klan, the Aryan Nation, and the National Alliance. The SPLC's paid informants ("field sources") engaged in the active promotion of racist groups at the same time that the SPLC was denouncing the same groups on its website.
The SPLC also had a field source who was a member of the online leadership chat group that planned the 2017 "Unite the Right" event in Charlottesville, Virginia. That field source made racist postings under the supervision of the SPLC and helped coordinate transportation to the event for several attendees.
In order to covertly pay its field sources, the SPLC opened bank accounts connected to a series of fictitious entities. The covert nature of the accounts allowed the SPLC to disguise the true nature, source, ownership, and control of the fraudulently obtained donated money the SPLC paid the field sources. In order to keep the scheme going, the SPLC made a series of false statements related to the operation of the accounts….
[T]he SPLC explicitly sought donations under the auspices that donor money would be used to help "dismantle" violent extremist groups. In the SPLC's solicitations for donations as outlined herein, donors were not told that some of the donated funds were to be used by the SPLC to pay high-level leaders of violent extremist groups and others, nor were donors ever told that some of the donated funds were used for the benefit of the violent extremist groups or that some of the donated funds would be used in the commission of state and federal crimes.
