California engineer admits to running San Antonio brothel, federal court records say

Derek Wai Hung Tam Sing pleaded guilty to running several sex-for-pay businesses, transporting workers across state lines

SAN ANTONIO – An electrical engineer from California admitted to running a brothel out of a Northeast Side massage parlor, according to federal court records.

Derek Wai Hung Tam Sing planned to enter a guilty plea on Tuesday, records show. The maximum penalty for this case is up to five years in prison and a $250,000 fine.

The Texas Attorney General’s Office and DPS began a five-year-long investigation into a spa owned by Sing on Austin Highway back in July 2017, according to the records.

The affidavit says the agencies discovered online posts about the spa, most recently operating under the name Meridian, and its employees offering sex-for-pay. The business also operated under at least two other names, including Green Tea Spa and Executive X.

After looking over bank, car rental, and airline records, investigators discovered Sing was traveling from San Antonio to California.

The affidavit reveals Sing was under investigation in California, where he was running another illegal prostitution business in Fresno and in Sacramento.

Text messages from the businesses included in the affidavit show that an hour-long session ran as much as $260.

Investigators discovered some of the women working in California had also worked for Sing in San Antonio.

According to the documents, California investigators seized the phones of three female workers.

After executing a search warrant, investigators discovered text between one of the workers and Sing, who used an alias.

The WhatsApp conversation, which spanned several days, included instructions from Sing on how much to charge customers and how much of the profit the worker was allowed to keep.

The affidavit says the worker sent multiple pictures to Sing of herself in lingerie similar to pictures connected with the Fresno and San Antonio brothels.

Records show that Sing has been convicted of corporate espionage.

About the Author:

Daniela Ibarra joined the KSAT News team in July 2023. This isn’t her first time in the KSAT newsroom– the San Antonio native spent the summer of 2017 as an intern. Daniela is a proud Mean Green alum, earning her bachelor’s and master’s degrees from the University of North Texas.