sentence1: The institute's breakthrough came about after it set out to examine Thür's belief that an octagonal tomb in the remains of the Roman city of Ephesus contained the body of Arsinöe. According to Roman texts the city, in what is now Turkey, is where Arsinöe was banished after being defeated in a power struggle against Cleopatra and her then lover, Julius Caesar.  Arsinöe was said to have been murdered after Cleopatra, now with Mark Antony following Caesar's death, ordered the Roman general to have her younger sibling killed to prevent any future attempts on the Egyptian throne.
sentence2: Queen Cleopatra ordered the assassination of her sister.