The surveillance of messages is admissible
1. in cases of kidnapping
2. in order to clear up a punishable act, committed with intent, which carries a prison term of more than six months, whenever the owner of the technical equipment agrees to the surveillance,
3. if this appears to be required to clear up a punishable act, committed with intent, that carries a
prison term of more than one year, or if the clearing up or prevention of a punishable act, committed or planned within the framework of a criminal or terrorist association or a criminal organisation (§ 278 to § 278b of the Criminal Code) would otherwise be essentially impeded, and
a. the owner of the technical equipment, which was or will be the source or target of messages is urgently suspected of a punishable act, committed with intent, that carries a prison term of more than one year, or of a punishable act pursuant to § 278 to § 278b of the Criminal Code, or
b. it is to be expected, on account of certain facts, that a person urgently suspected of the offence (letter a) will use the technical equipment or will establish contact with it;
4. if it is to be expected, on account of certain facts, that the whereabouts of a fugitive or absent accused may be determined, who is urgently suspected of a punishable act, committed with intent, that carries a prison term of more than one year.