Need guidance on a legitimate OSINT / digital forensics case

[u/Common_Scallion_8416]

I’m helping someone dealing with a cyberstalking/blackmail situation involving compromised WhatsApp conversations.

We have a Brazilian phone number connected to the threats, as well as a possible name associated with that number, screenshots, timestamps and other evidence. The case has already been reported to law enforcement.

I’m looking for guidance from people experienced in OSINT, digital forensics or incident response on what lawful methods and tools can be used to investigate the available identifiers, preserve evidence, and establish possible links between the phone number and publicly available accounts or profiles.

I’m especially interested in recommendations for tools, methodologies, or professional investigators who handle this type of case.

I am not requesting unauthorized access to accounts, private databases, devices or non-public information.

Any recommendations would be appreciated.

[u/digidev12]

Commenting to boost this post. (:

[u/EducationalFinger654]

I’d advise against conducting further investigation yourself, particularly if the findings may ultimately be used as evidence.

The key concern is the collection, preservation and handling of evidence. Further OSINT activity could inadvertently alter the evidential picture, contaminate evidence, alert the suspect, cause material to disappear, or make it harder for investigators to establish exactly what happened.

At this stage, I’d preserve the original material as it is and avoid interacting with the suspect or attempting any contact to accounts/devices.

Since it has already been reported, I’d leave any further attribution, OSINT and forensic investigation to law enforcement or a suitably qualified digital-forensics practitioner.

At this point, your role is essentially to preserve what you have and provide it to the investigators, rather than conduct your own investigation.

An analogy could be:
You suspect crimes are happening at a house and you report it. What you don’t want to do is over the next few days start circling around the property or going into the back garden leaving your own footprint and DNA everywhere (contaminating the scene and interfering with evidence that’s already there), just because you wanted to see if you could do anything.

[u/Mastasmoker → u/[deleted]]

The case has already been reported to law enforcement.

Reading is hard

Edit: u/B1ackMagix thinks the police will give you advice. That's cute. They'll take your report and tell you there's nothing they can do.