Now, I'm no great Constitutional scholar - my knowledge of Constitutional law being limited to having read the actual document and not having heard about it third-hand in law classes that none of my supposed classmates can seem to remember me having attended - but in my reading one has to be indicted by a Grand Jury before he can be tried for murder.
Amendment V
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.