If the missing woman is linked to entities involved in major fraud - and this seems to be the case as she is an officer in a corporation under investigation for fraud - IMO there are 3 possibilities.
The first is that Heidi flees to avoid an inevitable, impending prosecution. She changes vehicles in the apartment building, and leaves with as little as possible. She leaves the dog behind. She's traveling light. Due to Covid restrictions, fleeing abroad is more complicated than ever...
The second possibility (the most likely, IMO) is that an angry investor is in a rage, and has been defrauded by Ms. Planck and her associates of a huge amount of money. The investor confronts Ms. Planck, and realizes there is no hope of recovering invested funds. The investor kills Ms. Planck...
The third possibility is that Ms. Planck is under pressure to be a witness, and testify against her associates. The other parties in Camden Capital and its associated companies fear this, and her elimination is arranged....
My opinion and speculation only.