The Ministry of Primary Industries has been unable to determine how a rat's foot ended up on a Whanganui family's lunch plate.
Earlier this month, Gonville woman Candace Mosen said her son Lucas discovered the foot in a piece of saveloy he had put in his mouth.
The rest of the family had eaten from the same packet of Top Hat saveloys the previous night and were horrified at the discovery.
Tegel, which produced the product, issued a trade withdrawal while MPI collected the foot from Miss Mosen and a week later confirmed it was the left-front paw of a rat.
Last week MPI food compliance manager Melinda Sando said it had completed inspection of the premises the food was produced at, the production process and relevant records.
"MPI found no conclusive evidence to determine that the contamination occurred onsite," she said.
"Laboratory analysis confirmed that the foreign object was a rat foot. However the sample was handled before MPI received it for testing and this compromised the ability of the lab to undertake further analysis to assist with the investigation."
Miss Mosen accepted the foot had been handled and mixed with other food at the time it was served.
"I'm just a bit gutted that they couldn't prove anything."
She was pleased with steps Tegel had taken since and said she had been offered vouchers.
"That's really cool - I'm happy with that," she added.
Tegel said the matter was now closed "both with our consumer and internally".
Miss Mosen said she was unlikely to eat saveloys again.