When does a CEO (or the investor or the board) have to notify employees they will be unable to pay them for work already done?
Directors and officers (which includes executive officers like the CEO) but not investors have a duty to ensure that the corporation does not trade while insolvent. In this context, "trading" means incurring new debts and "insolvent" means being unable to pay their debts as and when they fall due.
Unfortunately, it is a judgment call by those directors and officers and the exact point where it occurred is generally only clear with hindsight, if then. For example, you describe a "tumultuous week"; quite likely the company was urgently seeking additional sources of funds and until it was clear they had no prospect of getting those, they weren't insolvent. The director's duty is to act reasonably (a broad range of activities) and not be overly pessimistic nor optimistic about the company's prospects.
As far as I know, they don't have a positive duty to inform their creditors that they can't pay. If that happens their obligation is to file for bankruptcy and their obligations cease - the bankruptcy trustee then invites creditors to prove their debts.
Does an investor have a responsibility to ensure all employees are paid?
No. That is pretty much the purpose of limited liability corporations: to shield the investor from the debts of the company.
Do the employees have any recourse?
Yes. Employees are typically priority creditors in Colorado and rank ahead of many other creditors. However, if the company is not based in Colorado different laws will apply.
Of course, you must be an employee of the company - this priority doesn't apply to true independent contractors.
Also, the liquidator's fees rank ahead of anyone and unless the bankrupt company has adequate realizable assets, even employees are unlikely to get a dividend.
You also need to be clear who you work for as you say "that last Friday was paid for/fronted by the HR company". Do you work for the bankrupt company or this (non-bankrupt) HR company? If the latter then they owe you your wages and the bankruptcy of their principal is their problem, not yours.
Is "secured debt" real? And does that reduce the likelihood of receiving a paycheck in a bankruptcy settlement?
There is a priority in the payment of creditors in liquidations and it varies by jurisdiction but a typical arrangement might go like:
- Liquidator's Fees
- Employee wages and entitlement accrued within the last 6 months
- Certain taxes
- Secured creditors (who may have a ranking among themselves)
- Unsecured creditors (including employee entitlements more than 12 months old, other taxes, trade creditors etc.)
- Shareholders (who may have a ranking among themselves)
Basically, the lower you rank, the less likely you are to see a dividend.
Does any of this change if the company doesn't file for bankruptcy?
Sure. Until the company does this it is still a going concern and it has to pay its debts. If it doesn't it's creditors can sue and recover their monies as best they can which may include forcing the company into bankruptcy.