If the subject of the harassment investigation is on an overseas business trip, is it acceptable to conduct a non-face-to-face interview?

Hello, I work in the HR department and am in charge of workplace harassment investigations.

There is currently one report filed, but it is reported that one of the subjects under investigation is on an overseas business trip and has no plans to return to the country for the time being.
We cannot delay the investigation for too long, so we are considering conducting the interview via video conference.
I understand that harassment investigation interviews do not necessarily have to be conducted in person, but I am wondering if there are any procedural issues if they are conducted remotely.
If we proceed via video call, I think we would also need to verify identity, check if the recording is being made, and ensure that others nearby are listening.
Also, since interview time is limited due to the time difference, it may be difficult to have a full conversation compared to an in-person interview.

In this case, I would like to know if it is better to conduct an initial remote interview first and then have an additional interview after returning home, or if it is acceptable to complete the investigation through a remote interview from the beginning.
How do you typically conduct surveys of subjects who are on overseas business trips or working abroad?