The family of a Sri Lankan woman who died in March while being detained at an immigration center in central Japan will soon file a criminal complaint against senior officials of the facility, sources close to the matter said Monday.

The move, expected as early as Tuesday, by the two younger sisters of Ratnayake Liyanage Wishma Sandamali, 33, is believed to be aimed at pushing the Nagoya District Public Prosecutors Office to further investigate the circumstances of Wishma's death.

Two sisters of Ratnayake Liyanage Wishma Sandamali, a Sri Lankan woman who died in March 2021 following mistreatment at a Japanese immigration center, speak to reporters in Tokyo on Sept. 10, 2021. (Kyodo)

According to a lawyer representing her family, while prosecutors began an investigation shortly after she died, it was not until September that they received security camera footage and other materials from the Nagoya Regional Immigration Services Bureau in Aichi Prefecture.

Wishma's family has accused the immigration authorities of failing to provide her with appropriate medical care, with their conduct amounting to willful negligence.

Wishma, who came to Japan in 2017 on a student visa, was taken to the facility in Nagoya in August 2020 after overstaying her visa. She died on March 6 while in custody after complaining of stomach pain and other symptoms from mid-January.

An investigation report released in August by the Immigration Services Agency of Japan found that staff at the facility lacked an awareness of how to handle crises, and there were problems with the center's medical and information sharing system.

Following the release of the report, the agency edited two weeks' worth of video footage showing Wishma before her death into around two hours and disclosed it to her family.

On October 1, the family and lawyers watched part of the footage at the Nagoya District Court as part of evidence preparation after having announced their intention to file a lawsuit seeking state compensation.

The Nagoya District Public Prosecutors Office in June accepted a separate criminal complaint filed by a supporter of Wishma, saying there was a failure to provide appropriate medical care to her.