Boom Logistics (ASX:BOL) said ongoing investigations into Ben Pieyre showed that the former chief executive misused less than AU$1 million of the company's funds, according to a Thursday filing with the Australian bourse.

The company has been looking into Pieyre's personal use of the company's credit cards and funds, and found "reasonable" evidence of his unauthorized spending on personal items and services for himself and others, the filing said.

Of the total amount misused, the company said it has recovered AU$246,720, adding that more extensive investigations are being undertaken to determine the full extent of the misconduct.

Pieyre resigned in July amid initial internal inquiries, per the filing.

The company's shares tumbled 4% in recent Thursday trade.