Insiders selling and not reporting the sales on Form 4 when the company is not current in its filings would be weapons-grade stupid.
If they are selling, the sales would have to be in private transactions and not the stock market. Under Rule 144, "Control securities" (any owned by insiders and affiliates) can not be sold publicly if the company is not current in it's 10-K/Q filings. Also, insiders/affiliates have to file Form 144 if they want to sell more than 5,000 shares in a public market.