Labour's Alan Kelly said he asked Garda Commissioner Drew Harris at the Oireachtas Justice Committee about the investigation leading up to that arrest.
A Dail committee has heard Gardaí engaged in a 'controlled delivery' of arms to Evan Fitzgerald, the man who died in the shopping centre shooting in Carlow earlier this month.
The 22-year-old from Kiltegan in County Wicklow was out on bail at the time, after being arrested last year near Straffan for possession of firearms.
Labour's Alan Kelly said he asked Garda Commissioner Drew Harris at the Oireachtas Justice Committee about the investigation leading up to that arrest - and how the guns had come into his possession.
Garda Commissioner Drew Harris said controlled delivery is used for both organised crime and "for our terrorist defence".
He said controlled delivery is "very sensitive police methodology".

Nationwide Fuel Protest Continues Into Third Day
Two Separate Weather Warnings Issued For Tomorrow
International Wholesale Prices Are "Not Price Gouging", Says CCPC
Costs Of Home Heating Oil Up By 67.5 Per Cent Between February and March
91-Year-Old Lelia Doolan To Arrive In Monasterevin Today As Part Of Her Walk For Peace
Harvey Norman Nationwide Cancer Fundraiser Launched
Operation Against Romance Fraud Network Leads To Arrests In West Dublin
Tánaiste Says Fuel Prices Should Drop Sooner Rather Than Later