Complex sentence: This case, which originated in Missouri, involved Christopher Simmons, who in 1993 at the age of 17 concocted a plan to murder Shirley Crook, bringing two younger friends, Charles Benjamin and John Tessmer, into the plot.
Split into simpler sentences: This case, which originated in Missouri, involves Christopher Simmons, who at the age of 17, committed murder. Mr. Simmons concocted the plan to murder, bringing two younger friends-Charles Benjamin and John Tessmer, into the plot.