Need help on removing buzzing sound while preserving quality.

Salutation to the forums, my reason for posting here is to ask for help on how to improve an important file that I need for Court.

When my brother recorded an incident that occurred from a neighbor and her friend who was threatening his life, he was not aware of any damage on his phone and in result the audio is greatly affected with a loud buzzing sound. I have made numerous attempts on my own to remove the buzzing, but doing so has made the voices of the neighbor sound robotic.

I ask if any reader is aware what suggestions can I do to effectively remove the buzzing sound and increase the volume of the neighbor’s voice? I will be infinitely grateful if any individual can give me advice, as since the Police informed us they refuse to take the video since the buzzing is too loud. I have literally tried for four years to try and improve the quality for the whole video.

If my actions are permissible, I will share two files with one being unedited. I am not able to attach the files since the two are large, so I am sharing from if that is okay. If no, I can use Dropbox. There is some mild language, but not excessive and vulgar. If the files are not permitted, a moderator can please review them.

Here is the unedited:
Here is the edit version of what I was able to do on a program called Reaper:

I’m not a lawyer, but I very much doubt that the audio will be permissible if it has been “doctored” (modified in any way). I suspect that they are just trying to politely say that they don’t want to get involved.

Any attempt to remove the hum will do some damage to the audio, particularly to the quieter audio. The most “authentic” sound is the unmodified audio.

Noise-reduction creates digital-artifacts, sometimes the artifacts sound like speech which wasn’t there.