SOUTH BEND, Ind. – A federal judge on Thursday sentenced the owner of a peptide company to nearly six years in prison after finding he built a massive business by deceiving customers and selling products that were adulterated with steroids.Matthew Kawa, who ran Paradigm Peptides, pleaded guilty last year to selling unapproved drugs and illegally importing them from abroad. His sentence marks a rare criminal penalty for a seller of peptides that are labeled "for research use," a largely unregulated marketplace that has become a go-to source for many people who look beyond established medical channels for ways to boost their…