Whoever gives or fabricates false evidence, intending thereby to cause, or knowing it to be likely that he will thereby cause, any person to be convicted of an offence which is capital by this Code, or under any other law for the time being in force, shall be punished with imprisonment for life, or with imprisonment for a term which may extend to 20 years, and shall, if he is not sentenced to imprisonment for life, also be liable to fine; and if an innocent person is convicted and executed in consequence of such false evidence, the person who gives such false evidence shall be punished either with death or the punishment hereinbefore described.