The word you are looking for is 'bloodcurdling'. It can't refer to a person, however. It is usually a sound or an image which is described in this way.
The commonest collocation is with 'scream'. For example, 'When she saw the body she let out a bloodcurdling scream.'
'Curdle' is what happens to milk when it separates out into hard lumps. These lumps are called 'curds'. The suggestion is that the person's scream was so loud and frightening that it made your blood go solid.