A grand jury in Massachusetts has indicted a former Boston College student in the suicide of her boyfriend, whom prosecutors said she verbally, physically and psychologically abused right up to his death.

South Korean national Inyoung You, 21, was charged with involuntary manslaughter in the death of fellow Boston College student Alexander Urtula, 22, the Suffolk County District Attorney's office said in a statement on Monday.

The statement said You used her cellphone to track Urtula's location to a parking garage in the Roxbury neighbourhood of Boston and was present when he leapt to his death on May 20 at around 8:35 a.m., hours before he was set to attend his graduation ceremony from the private university.

In the two months before his death, the couple exchanged more than 75,000 text messages, with You repeatedly urging Urtula to "go kill himself" and "go die," saying that she, his family and the world would be better off without him, the statement said.

An investigation showed You used attempts and threats of self-harm to control Urtula and isolate him from friends and family, the prosecutors' statement said.

"The abuse became more frequent, more powerful and more demeaning in the days and hours leading up to Mr. Urtula's death," the statement added.

You is in South Korea and authorities are cautiously optimistic she will voluntarily return to the United States, Suffolk County District Attorney Rachael Rollins told a news conference.

A biology major, Urtula was from Cedar Grove, New Jersey.

You was aware of Urtula's spiralling depression and suicidal thoughts but continued to encourage him to take his own life, the indictment said.

The events have some similarities to another Massachusetts case in which Michelle Carter, 23, was convicted of involuntary manslaughter in the 2014 death of her boyfriend, Conrad Roy, who was 18 at the time.

It was not immediately possible to contact You or establish if she had an attorney representing her.