Samoa's Ministry of Environment is sending a mongoose caught at the weekend to New Zealand for further tests to try and find out where it came from.
Mongooses had not been in Samoa until late last year when there were several reported sightings.
The Ministry's assistant CEO, Faleafa Tony Tipama'a, says traps from New Zealand were used to catch the mammal that got into Samoa by unknown means.
He says it is thought to have come from either from Fiji or Hawaii.
"We'll also be sending it to New Zealand to see whether its actually the ones from Fiji but it looks like this mongoose is also a regional Indian mongoose."
Faleafa Tony Tipama'a says officials are maintaining traps in case there is more than the one mongoose.
The Ministry of Agriculture has also planned a biosecurity training workshop next month to improve quarantine measures.