Application for the writ is made by petition, signed either by the party for whose relief it is intended, or by some person in his behalf, and must specify:
1. That the person in whose behalf the writ is applied for is imprisoned or restrained of his liberty, the officer or person by whom he is so confined or restrained, and the place where, naming all the parties, if they are known, or describing them, if they are not known;
2. If the imprisonment is alleged to be illegal, the petition must also state in what the alleged illegality consists;
3. The petition must be verified by the oath or affirmation of the party making the application.