A not guilty verdict has been finalized for a South Korean drug importer who was caught attempting to bring in methamphetamine from Mexico by international parcel, as prosecutors seized the illegal import without obtaining a confiscation warrant from a judge, the Supreme Court said Monday.

The top court said it has upheld a lower courts' decision to acquit the drug importer, identified only as 50-year-old Ma, of all criminal charges in the 2011 import of 99.2 kg of meth, noting prosecution investigators failed to secure a court warrant before and after their seizure of the drug.

Ma was arrested in June 2011 and indicted later after the prosecution was tipped off about meth concealed in some parcels arriving from Mexico at Incheon International Airport, west of Seoul, and enlisted the help of customs officials in the detection of the illegal drug in a parcel addressed to Ma.

In the process of searching and seizing Ma's parcel, prosecutors didn't ask for any warrant from the court. Ma was additionally charged with importing meth worth 10 to 100 grams each on six occasions from December 2009 to April 2011.

Confirming Ma's not guilty verdict, the Supreme Court said a court-issued search and seizure warrant was indispensable in the case, because investigators opened and examined a specific shipment and confiscated its content. It also ruled that Ma's other drug charges before 2011 cannot be backed by sufficient evidence.

The top court has said search and seizure should be carried out in accordance with the due legal process to protect basic human rights.

Under the current laws, the import or export of meth, a banned substance in South Korea, can be punishable by imprisonment of over five years, with habitual violators subject to the sentence of a jail term heavier than 10 years.

Prosecutors facing criticism that they failed to penalize a drug criminal despite securing decisive evidence claimed that Ma's parcel was simply handed over by customs officials, instead of being seized. (Yonhap)