According to this article, found in the Utica Press Dec 22, 1976, Madonna imported his heroin from Bangkok, Thailand. At least that was what he was convicted of.

"Convicted Man Draws Maximum Term"

"A 41- year-old Bronx man
convicted with two others
of conspiring to smuggle 12
pounds of heroin from
Bangkok to New York, was
sentenced Tuesday to a
maximum term of 30 years
in prison and fined
$50 000.
In imposing the sentence
on Matthew Madonna,
Judge Robert L Carter
said it was the "hardest
sentence I have ever inflicted
and hope never to
have to impose again".
The sentence consisted
of 15 years each on two
counts to run consecutive
and a $25,000 fine on each
count and was the maximum
the court could have
imposed.
Salvatore Larca 32, also
of the Bronx who Judge
Carter characterized as a
"junior partner" in the
conspiracy, also received
two 15 year terms but to
run concurrently
The third man, Richard
Klinger 34 of Orange-
Calif, was sentenced to six
months in prison and
placed on probation for 18
months. The judge said
there was no evidence
Klinger had been involved
in a large scale operation."