Then in 1966, Mandagi attended a course on military courts until she was appointed Head of the Maluku Regional Police Section on Legal Affairs.

Mandagi's interests in preventing drug abuse began to be pursued by taking the United Nations Regional Course on the Control of Narcotics in 1974.

One year later, she attended a drug law enforcement course in Washington, D.C.[2] After receiving several training certificates, Mandagi worked at the National Police Headquarters in the narcotics office in 1976.

[4] Due to her vested interest in drug eradication in Indonesia, even in retirement, she was entrusted to serve as an expert adviser to Police General Tito Karnavian[5] and chaired the Indonesian Anti Narcotics Law Enforcement Retirement Association (AP2ANI or Ketua Asosiasi Purnawiran Penegak Hukum Anti Narkotika Indonesia).

[7] Jeanne Mandagi died at the age of 80 on 7 April 2017 and was buried in the Jagakarsa Public Cemetery in South Jakarta.