Elves are finding it really hard to stay here for very long without singing but they borrow the eyes of their colleagues in Cene who are talking trade agreements in a pretty skyscraper and cope.

Reds go to work. Eventually some of them come back. Reds move between red buildings. Kids play in the street, a little, carefully out of view of the exits.

Not all the ones who went to work come back?

Not yet, anyway.

They wait and sing oh so very quietly.

Too quietly for reds to hear?

...mostly?

Some of the kids notice. They pause, listening suspiciously.

Very very quiet singing.

The kids bolt. Soon the streets are cleared out again. Work vehicles continue to come and go but give the singing Elves a wide berth.

It is kind of horrifying that these people are so terrified. The Elves do not leave.

Reds continue to go about their business and go nowhere near Elves.

Elves remain determined to wait this out, since there is nothing else useful to do in their entire assigned country.

It does eventually become clear that not all the reds are coming back from work.

Uh huh.

They have a forensics demon look that up.

Couple of them went to work and got murdered.

By police or just random people at their place of employ?

One of each!

Vanda Nossëo sends Rivik a courtesy notification that there's an investigation into loss of life in connection with interdimensional contact and that galactic observers will be present for the foreseeable future, as will the media. Should Rivik choose to cooperate with the criminal investigation into the murders, the observers are equipped to collaborate with them and provide forensic support and factfinding; should Rivik find that events do not merit prosecution under local law, Vanda Nossëo will handle it all themselves. 

Rivik says that they haven't signed anything and Vanda Nossëo is to leave their citizens alone.

Vanda Nossëo has made the following arrests for murder in connection with the ongoing investigation. They understand that extended contact can cause all kinds of problems and will keep the observers and investigators as unobtrusive as possible; most Rivikni citizens should never even see one, and they'll wrap up the investigation as quickly and neatly as they can.

...they can't have those citizens they arrested and should give them back.

Here's the case summary, should it be of interest to Rivik's government!

Are they deaf? Here it is in sign.

Recently Vanda Nossëo insisted that some planet that was practicing slavery stop that. A regional governor murdered all his slaves. This was legal under local law. He was still arrested and convicted under galactic law. He appealed. He did not win his appeals.

Or, in clearer language: no.