Matthew 2:7

Then Herod privily called the wise men, and learned of them exactly what time the star appeared. And he sent them to Bethlehem, and said, Go and search out exactly concerning the young child; and when ye have found him, bring me word, that I also may come and worship him.

Herod's duplicity was in keeping with his evil character. He did not wish to worship the Christ child but to destroy him! He knew the birthplace; he thought he knew the child's age; and it remained only to find the exact location of the Christ child in order to slay him. That there was real danger in this plot appears from the fact that God himself intervened both in the behavior of the wise men and in the departure of Joseph to Egypt.