Sometimes serious accidents occur on construction sites or in companies, whether a scaffold was built incorrectly or employees in a factory ignore labour security regulations and operate equipment improperly. Also major accidents in traffic can happen due to negligence.
Such incidents involving personal injury or property damage regularly cause a police operation with corresponding investigations.
The investigations are usually directed against persons who were somehow involved in the event. Often it depends on chance whether someone becomes a defendant. Criminal investigations may also be initiated against managing directors and executive staff of a company in case of failure of organisation (e.g. due to lack of training or missing supervision of the staff).
There are not only criminal consequences, but also professional or disciplinary consequences. Criminal investigations often precede civil claims for damages against the company.
In any case, get advice before you face interrogation or answer questions from investigators. Everything you say can be used against you.