undetected

The theft went undetected until a cleaning lady arrived for work in the morning and alerted authorities.

"And when they have penetrated your networks, they actively and aggressively map your systems, and seek to maintain persistent undetected access that enables them to conduct sabotage at a time and moment of their choosing."

That allowed the team to go undetected as they prepared to break into the palace.

Ultimately, though, trying to unpick the precise reason for why our food and drink costs what it does is very difficult - other factors that influence price can go undetected.

Narco-subs have become a popular way to transport drugs as they can go largely undetected, and can be sunk after delivery.