JAKARTA, Indonesia — Two are young Australians portrayed back home as generally good lads. One is a Brazilian who is mentally ill. There are four Nigerian men, a female migrant worker from the Philippines and an Indonesian laborer.

They come from diverse backgrounds and circumstances, but all nine were convicted of drug crimes in Indonesia. And all are scheduled to die soon in a mass execution on a remote island off the southern coast of Java.

In what is believed will be the largest such execution in Indonesia in decades, firing squads could start the job as early as 12:01 a.m. on Wednesday.

A 10th convict, a French citizen, had been part of the group but won a last-minute, two-week reprieve late Saturday night, according to a spokesman in the attorney general’s office, Tony Spontana. Mr. Spontana said the decision involved “an issue with the high courts” but provided no further explanation.