Ukrainian pre-trial investigation is governed by the Criminal Procedure Code of Ukraine (Кримінальний процесуальний кодекс України, law 4651-VI), and its structure is worth understanding by anybody working with Ukrainian material.
How a case begins. There is no separate decision to "open a case". Under Article 214, an investigator or prosecutor must enter information about a criminal offence into the Unified Register of Pre-trial Investigations (Єдиний реєстр досудових розслідувань, ЄРДР) within 24 hours of learning of it, and the investigation begins at that moment. The register entry is the starting point from which every deadline runs.
Who leads. The prosecutor directs the pre-trial investigation and is accountable for it; the investigator carries it out. Certain acts — searches, most covert measures, detention beyond the statutory period — require a ruling from an investigating judge.
The inspection of the scene. The scene inspection (огляд місця події) is the one investigative act the code permits before the register entry, because a scene cannot wait. Everything else follows the entry.
What this means for the association's members. Material gathered outside these procedures is not evidence in a Ukrainian criminal case, however truthful it is. It can be intelligence, it can be a lead, it can be handed to an authority — but a photograph taken by a volunteer is not an inspection protocol, and presenting it as one damages both the material and the person who offers it.
Sources. Criminal Procedure Code of Ukraine, law 4651-VI, Articles 214 and 237, published by the Verkhovna Rada at https://zakon.rada.gov.ua/laws/show/4651-17 ; National Police of Ukraine, https://www.npu.gov.ua/ ; Office of the Prosecutor General, https://www.gp.gov.ua/
Note. The Rada's site asks automated clients not to fetch its law pages, and this platform respects that: the articles above are cited from the published code by number so that a reader opens it themselves.