Is this standard phrasing? As a non-native speaker this sentence seems odd. I'd have guessed that fact and allegation are xor. The sentence implies that there can be facts that are also allegations (or treated as allegations).
Criminal complaints are written as if everything in them is a true fact, unlike, say, newspaper articles that use phrases like "the alleged thief."
For example, a newspaper article about this complaint would say things like "The FBI's criminal complaint alleges that..." - even though the complaint itself states it as a fact.
Generally, one shouldn't present allegations as facts (use phrases such as 'allegedly'), but doing so is standard for criminal complaints.
The phrasing probably comes from the legal-style-wording in which I imagine they are trying to ensure they are not able to be sued by the defendant under e.g. defamation by presenting their facts (by saying they are all allegations not facts, they cover all of their bases).