A Yonkers woman posing as a cosmetologist has been convicted of administering a deadly dose of silicone to a patient. The woman, 58-year-old Elsa Then, was found guilty of criminally negligent homicide in the 2009 death of 43-year-old Fiordaliza Pichardo. Authorities say Then had pretended to be a licensed cosmetologist when she gave Pichardo silicone injections to enhance her thighs and buttocks. Authorities also say Then tried to close Pichardo's wounds with paper towels and Krazy Glue. Doctors say the surgery caused a blood clot, which led to her death. Then faces up to four years in state prison and is scheduled to be sentenced Dec. 12.Woman: Botched plastic surgery killed my mom