Randall Garrett 
Unwise Child 

After two unsuccessful and seemingly random attempts on his life in the space of as many hours, Michael Raphael Gabriel finds himself called on to act as engineering officer on a new type of spacecraft designed for one mission only, to carry a giant computer to a distant destination before it can destroy the Earth. But once underway he discovers there is a murderer on board and the computer has gone crazy in… Unwise Child!