Complex sentence: Coming upon canceled checks, he noticed some were made out to high-profile New York gambler Arnold Rothstein between November 10,1920 and November 9,1921, the Fuller firm wrote $187,000 worth of checks to Rothstein.
Split into simpler sentences: Coming upon canceled checks, he noticed some were made out to high-profile New York gambler Arnold Rothstein. Between November 10,1920 and November 9,1921, the Fuller firm wrote $187,000 worth of checks to Rothstein.