photo by: Johnson County Sheriff's Office

In this mugshot provided by the Johnson County Sheriff's Office, Robert J. Gross is pictured following a 1987 arrest by the Merriam Police Department.

A man accused of inappropriate sexual behavior at area massage parlors — including allegedly stripping naked and groping a worker at one in Lawrence — has been convicted of federal stalking and gun charges.

The conviction of Robert J. Gross, 67, of Kansas City, Mo., is the latest installment in a criminal history that dates back decades and allegedly includes even more sinister crimes.

“Gross has a history of interest in prostitutes, including deviant sexual and violent behavior, particularly against women, dating back to at least 1975,” according to the complaint against him in the federal case. A recent six-part investigation by The Kansas City Star identified Gross as a suspected serial killer linked to stalkings and unsolved murders of several women in the Kansas City area, including two who worked in the massage business. Gross has not been charged in any of the homicides.

In the new case, a federal jury in Kansas City on Wednesday convicted Gross of two counts of stalking victims across state lines, three counts of being a felon in possession of a firearm, and three counts of receiving a firearm while under indictment, according to a news release from Timothy Garrison, U.S. Attorney for the Western District of Missouri.

Gross’ trial began Monday, and the jury deliberated two hours before returning its verdict, according to the news release. Gross, whose sentencing hearing will be scheduled later, could face up to 55 years in federal prison without parole. 

Federal authorities began surveilling Gross after Oct. 1, 2017, when he allegedly sexually assaulted the worker at Lawrence’s Tea Spa Massage, 2223 Louisiana St.

Surveillance video of the Lawrence massage parlor incident — as described in court documents — shows Gross walking through the business completely nude.

At the front counter, he caresses the worker’s face as she pulls away, makes a lewd gesture, then tries to grab her face again. While still completely naked, Gross wraps his arms around the woman from behind, fondles her breast as she turns away, and slaps her buttocks.

According to federal and Douglas County court filings:

Also that day, employees of some Olathe massage businesses reported to Olathe police that their cars had been vandalized — keyed, tires flattened by screws, and windows broken out — at their homes and work.

A woman who owned one Olathe massage business, managed another Olathe massage business and also worked at Tea Spa told police she suspected Gross, whom she knew as “Bob,” had followed her and other workers home. She said he’d been coming into all three businesses since January 2017, initially to request massages but later in search of “sexual services.”

In connection with the sexual assault of the 56-year-old woman at Tea Spa, Gross was charged Oct. 24, 2017, in Douglas County District Court with one count of aggravated sexual battery, a felony. He was arrested on the charge Nov. 7, 2017, posted a $5,000 bond and was released the same day.

In the following months, Gross began purchasing handcuffs, ski masks, black shirts labeled with “SECURITY,” and guns from various businesses and individuals in the Kansas City area, according to federal court documents. In late December, law enforcement closed in on him during a gun buy in a parking lot and made an arrest.

That evidence and reports from the massage workers led to the federal charges of which Gross was convicted.

Gross’ Lawrence sexual battery case has been at a standstill since his arrest in the federal case.

The Douglas County Sheriff’s Office previously denied the Journal-World’s request for Gross’ booking photo.