Her words are really powerful:
Mr Mckeague's mother Mrs Urquhart said: "The police have behaved in such a way that they have utterly destroyed any faith or trust I have in them actually trying to do something to find Corrie.
"They have absolutely destroyed my belief that they are competent and they know what they're doing.
"This is more than just resources, this is an utter betrayal of trust."
It sounds to me that the police have done something that she just found out about and she snapped. She says it's not just about resources (so I don't think it means the investigation as a whole), but the "utter betrayal of trust" let's on that it is very serious, this breach.