EB-1A letters of recommendation
USCIS says letters of support should not form the cornerstone of the claim. Officers expect the statements to be corroborated.
What to ask a writer for
Who they are, how they know the work (preferably not as your manager), what is original, who else uses it, and where that can be checked. A generic “leading expert” paragraph without exhibits is a common RFE theme.
This is not a law firm and does not file petitions. USCIS decides each case on its own record.