The family of Yongsang Soh has officially filed a lawsuit against Washington University, claiming that the school’s handling of student drug cases led to Soh’s death.

A senior at the University, Yongsang Soh fell from a 23rd-floor balcony of The Dorchester on Forest Park on Oct. 26, 2013. His death was initially ruled a suicide, but according to Michael Graham, the chief medical examiner for the City of St. Louis, the manner of death was changed to “undetermined” as a result of an independent examination pursued by Soh’s parents, which found LSD in their son’s body.

The lawsuit, filed Monday, alleges that the University was negligent in its treatment of drug cases on campus, putting students such as Soh in danger. Central to the suit is the family’s claim that after a series of drug investigations and violations among Sigma Alpha Mu fraternity, of which Soh was a member, SAM members were not referred to criminal prosecution and were instead dealt with within the University’s own judicial system.

Jill Friedman, vice chancellor of public affairs for the University, disputed this claim in a statement last week.

“After a complete and fair investigation into activities related to the Sigma Alpha Mu fraternity chapter, the University took serious disciplinary action against involved students up to and including permanent termination and referred individual cases to the local prosecutor for consideration of criminal charges,” the statement said.

Ed Magee, spokesman for the St. Louis County prosecutor’s office, said that while specific information about SAM referrals was not available, over the last four years, 155 cases have been referred from the Washington University Police Department to the county prosecutor’s office.

Magee added that while the 155 cases included a variety of felonies such as burglaries and sexual assaults, at least some were for felony drug charges. Because additional cases might have been referred to the City of St. Louis rather than St. Louis County, the total number of cases referred by WUPD might be greater, he said.

Albert Watkins, the Soh family’s attorney who filed the lawsuit, was skeptical of the 155-case number, questioning how many of WUPD’s referrals were of students rather than others under its jurisdiction.

Watkins also referenced a letter sent from Soh’s parents to Chancellor Mark Wrighton in June, which claimed that no University students were criminally prosecuted in the last four years for “drug offenses occurring on campus and investigated by WUPD.”

Magee did not have information from the prosecutor’s office about how many of the 155 cases were students or how many led to charges.

“We review them to see if we have probable cause to charge the person based on the investigation, and if they do, we charge the person and it’ll work its way through the court system,” Magee said. “And if there’s insufficient information to believe we have probable cause, then we refuse the case or we refer it for additional investigation if it can be done.”

While the family asked for a $50 million settlement from the University in the letter sent in June, Monday’s lawsuit did not specify a requested amount.