What must be weighed before using undercover investigation, and what does the "fake fortune teller" case show?
Whether it is proportionate for the state to commit offences (forged documents, deception) to solve an offence; whether the suspicion is strong enough to justify the trust that is abused; and whether the evidence obtained can be used in court.
Three questions:
- Proportionality: the investigator commits acts that would otherwise be crimes, such as forging documents and deceiving people, to solve a crime. That is acceptable only if the crime being investigated is much more serious.
- Substantiated suspicion and abuse of trust: the method works by winning the target's trust and then betraying it, so the suspicion must be well founded first.
- Admissibility of results (Verwertbarkeit): evidence obtained by deception can be thrown out by the court, and then the whole operation was for nothing.
The case: in a 2009 homicide in Zurich there was no confession and too little evidence. An undercover operation faked a friendship with the suspect and then a fortune teller, who drew out a "confession". The district court sentenced him to 14 years (2018), the high court of the canton acquitted him (2020), and the prosecution appealed to the Federal Supreme Court (judgment 6B_210/2021). In 2022 the Federal Supreme Court dismissed the appeal: the confession was inadmissible, because the investigators had exploited the man's belief in the supernatural and stoked his fears to build massive psychological pressure, which in effect got around his right to remain silent. The acquittal stood. The court still held that undercover investigation of a crime already committed is allowed in principle, but warned that such pressure can push even innocent people into false confessions.
Go deeper:
SRF: Murder confession obtained through a fortune teller is void — the Federal Supreme Court's ruling (German).- law.ch: Excessive pressure by undercover investigators — the legal reasoning of judgment 6B_210/2021 (German).