Casellas, a wealthy insurance broker, was arrested as he arrived at a court in Bayamon with his lawyers and two bodyguards.
The 47-year-old father of two is also charged with destroying evidence, making a false report and weapons violations stemming from the July 14 shooting death of his wife Carmen Paredes Cintron, who was killed at their home in the prestigious San Juan suburb of Guaynabo.
Casellas did not enter a plea but has denied killing his wife. A judge set a preliminary hearing for September 18 and set bail at US$4million, which Casellas paid.
The high-profile case has attracted widespread attention in Puerto Rico because of the circumstances of the crime and the fact that Casellas comes from a prominent family.
He is the son of US District Court Judge Salvador Casellas, a former Puerto Rico treasury secretary who was appointed to the federal bench in 1994 by President Bill Clinton.
His 46-year-old wife was shot dead near the swimming pool of the family’s home in an exclusive gated community.
Casellas reportedly told investigators that he came home from visiting his parents to find his wife dead and an unknown assailant jumping over a fence. He claims to have shot at the man but missed.
He is also said to have claimed that he had been carjacked earlier in the day after visiting a shooting range and that the assailants stole a gun that was the same calibre used to kill his wife.