 Soisalon-Soininen worked at the senate's justice apartment from 1900 and from 1901 to 1905 as chancellor of justice.Soisalon-Soininen was assassinated in 1905 when a young student called Lennart Hohenthal murdered him at his apartment in Helsinki.In the morning at 10.30 AM a young man of a heavy build (Hohenthal) dressed as a Russian officer came to Soisalon-Soininen's apartment in Helsinki.