Fear of Strangers — E.C. Tubb

Instead of the welcome they'd expected, the returning crew of the first interstellar spaceship were kept in space, imprisoned in their craft. In quarantine, as carriers of a deadly alien disease! When the prisoners escaped, the worried authorities hired Earth's top detective Martin Slade to track them down, little suspecting that Slade had his own personal agenda to find the men. Slade's search for the missing crew spans millions of miles of space, following a trail of hideous deaths . . .