In brief

An investigation needs only an initial suspicion: concrete facts that make an offence appear possible. At this stage the law does not yet require probability.

Section 152(2) StPO obliges the public prosecutor to act on all prosecutable offences where there are sufficient factual indications. This is the principle of mandatory prosecution, and initial suspicion is the threshold at which that duty begins. Facts are required, not mere assumptions, and police experience may not simply fill the gap between the two.

Higher levels of suspicion differ in the degree of probability. An indictment requires sufficient suspicion, meaning a conviction is more likely than not (Sections 170(1) and 203 StPO). An arrest warrant requires strong suspicion, a high probability (Section 112(1) StPO).

Where suspicion comes from

Usually from a criminal complaint. That may come from a neighbour, a former partner, a store detective, a bank filing a money laundering report or a job centre after a data match. The last two in particular are largely automated: a comparison shows a discrepancy, the authority reports it, the prosecutor opens a case. Whether there is really an offence behind it is still open at that point.

The threshold is low and courts review it cautiously. It matters in practice when coercive measures follow a thin suspicion. A search warrant under Section 102 StPO also requires only initial suspicion. The Federal Constitutional Court insists, however, that it rest on concrete facts and not on vague indications or assumptions. Warrants fail on this point time and again.

What this means for you

Anyone who receives a summons or a written questionnaire is an accused person in a case that so far rests on initial suspicion. That is a long way from a conviction. A large share of German criminal cases ends without charges, many of them under Section 170(2) StPO because the suspicion was not confirmed. Our approach during the investigation is therefore rarely to prove innocence. Usually it is about showing that the initial suspicion does not become a sufficient one.

General explanation, not advice on an individual case. As of November 2026.