Crimes committed at sea present a ‘dynamic legal scenario’ where international law recognises a multitude of domestic jurisdictions existing concurrently..
Any crime that can be committed ashore can also be committed onboard, such as a theft, sexual assault, rape or murder. If there is criminal activity on board it is important to stop the criminal activity and to investigate the crime so that perpetrators may be brought to justice. Similar to the case of a piracy attack, any suspicion of criminal behaviour and certainly any crime carried out should generate a post incident report and be reported immediately to authorities, such as the flag State and the port State, if the ship is in port, and to the shipowner. Reports should also be sent to the victim’s state as well as to the state of the suspected perpetrator. Where a citizen is involved in a criminal offence, either as an alleged perpetrator or as a victim, their country of citizenship is recognised under international law as also having jurisdiction to investigate and prosecute the crime.
H.8.2 How to Manage a Crime Scene
The IMO has specific guidelines that emphasize that the Master is not a professional crime scene investigator and does not act in the capacity of a criminal law enforcement official. Thus, Governments are encouraged to have trained investigators available who can collect the available evidence from a vessel immediately after its release from local authorities. Failing this, every effort should be made to have an investigator available at the vessel's first port of call after an incident. The investigator shall take crew statements and there are guidelines on recovery and packaging of evidence. Immediately after an incident, the Master, in cooperation with the PCASPs team leader if this is piracy related, should co-operate, protecting the scene of any incident including any potential forensic evidence that could lead to the later arrest and conviction of criminals/pirates as far as is practicable. The process is further outlined in the soft law regulations on PCASPs, such as the ISO standard on PCASPs.
 INQUIRY INTO THE ARRANGEMENTS SURROUNDING CRIMES COMMITTED AT SEA, Chapter 3,Jurisdiction at sea: international law and domestic law, Australia Government,
See supra at Piracy Attacks and the Use of Force.
 MSC.1/Circ.1404 (23 May 2011), Annex 1, GUIDELINES TO ASSIST IN THE INVESTIGATION OF THE CRIMES OF PIRACY AND ARMED ROBBERY AGAINST SHIPS, Introduction.
9.8  ISO Standard 28007 -1:2015. Ships and marine technology — Guidelines for Private Maritime Security Companies (PMSC) providing privately contracted armed security personnel (PCASP) on board ships (and pro forma contract)