A Thai-born student at American University, who boasted of receiving pure white Asian heroin in packages sent through the Royal Thai Embassy in Washington, has been sentenced in Montgomery County Circuit Court to five years in jail for conspiracy to sell heroin.

Suwannawat Thongtham, 26, of 3138 N. 10th St. in Arlington, who recanted the boast, could have received a maximum 20-year sentence on the charge. Thongtham, a graduate student in chemistry, will face deportation proceedings when he is released from prison.

Assistant state's attorney Tom Heeney had asked Judge H. Ralph Miller to sentence Thongtham to a maximum term, describing the stocky, blue-jean-clad defendant as "a major drug dealer . . . strictly a businessman who was (dealing drugs) for only one reason - to make a profit."

Judge Miller, despite his stating that he accepted the prosecution's contention that Thongtham reaped $14,000 from 18 drug transactions in 14 weeks before he was arrested last year, cited American Bar Association sentencing standards as his reason for imposing the five-year sentence.

Thongtham, who has been in jail since his arrest last May 13, will be eligible for parole in six months. If paroled, he would immediately face deportation proceedings for having been convicted of a crime, officials of the Immigration and Naturalization Service said.

Thongtham had pleaded guilty to the conspiracy charge in November, making a trial unnecessary.

However, in a legal procedure which allowed the prosecution to state its case against Thongtham, Montgomery County police vice officer Ronald A. Ricucci testified that Thongtham received the high-quality heroin concealed in tape cassettes and ornamental seashells sent to an aunt at the Royal Thai Embassy.

The packages were "stored" at the embassy until Thongtham picked them up, Ricucci said.

Thongtham, who had been in the country on a student visa since 1972, then sold the heroin at a pace of $1,000 a week to three distributors. The distributors in turn sold the drug to a group of 25 addicts in the Twinbrook section of the county, Ricucci testified.

Ricucci later told a reporter that he didn't know the name of the alleged aunt, but had relied instead on three witnesses who independently repeated what Thongtham had told them. Embassy officials denied any knowledge of Thongtham and said the heroin couldn't have come through the embassy's diplomatic pouch.

Thongtham, when Miller asked him if he wanted to make any statement before being sentenced, said he had made up the story that he had relatives or friends in the embassy "to make me look important." He said he bought the heroin in Washington.

Thongtham's arrest and the prosecution's case was based on information from a man who had purchased heroin from Thongtham on 18 separate occasions before having a him. The man was granted immunity from prosecution.