6E

Why do you think the code killer killed for McCaleb?

So McCaleb would have to live with the guilt of knowing Gloria and the other two were killed to provide him with his transplanted heart - something he would remember with every beat of his heart for the rest of his life.

He wanted him to feel guilty for his heart.

What a horrible thing to do! As if he wasn't already feeling some degree of guilt that someone had to die so that he could live.

The killer wanted McCaleb to think of him every day…with every beat of his heart. True evil. McCaleb bested him so he wanted revenge, and to prove that he won in the end.

One way to get back at McCaleb and something that would affect him for ever and a day.