Montgomery Co. gymnastics coach indicted for sexually abusing 2 minors

A gymnastics coach in Montgomery County, Maryland, has been indicted for sexually abusing two young people, and police detectives believe there may be more victims.

Mark Samuel Yellock, of D.C., was an instructor at Silver Stars Gym in Silver Spring, and Dynamite Gym in Rockville, when he allegedly sexually assaulted and had sexual contact with a girl, who was 13 when the abuse began, in 2005. She is now 28.

According to charging documents, the investigation began in April 2020 with U.S. Center for SafeSport — a Denver-based nonprofit that addresses the problem of sexual abuse of minors and amateur athletes. Three months later, Montgomery County police began their investigation.

Yellock was indicted this week on six counts: sex abuse of a minor, second-degree sex offense, and four counts of third-degree sex offense.

On Friday, Montgomery County Police’s Special Victims Investigations Division — Child Abuse Unit issued a news release, urging those who believe they have information, or believe they are a victim to contact police.

Court records obtained by WTOP showed that Yellock was also indicted earlier this week in a similar case, with a second young victim, that allegedly occurred in 2014.

With the second victim, Yellock was indicted on two counts: sex abuse of a minor and third-degree sex offense.

Police and prosecutors have not provided information about the recent incident or specifics of how Yellock was acquainted with the second young victim, although the nature of the charge includes his being in position to supervise the child.

Yellock’s attorney, Esteban Gergely, did not Immediately return a request for comment.

Court records show prosecutors and the defense have agreed to have Yellock tried separately, with different judges, for each victim.

Yellock is scheduled to go on trial for the 2005-2007 incidents Jan. 10, and on Jan. 24 for the 2014 incident.

Typically, defendants charged with similar crimes against multiple defendants choose to have the cases tried separately, to avoid the possibility of a jury believing he is a serial offender.

Yellock is being held without bond

Montgomery County police asked anyone with information about the case to call the Special Victims Investigations Division at 240-773-5400.

WTOP’s Anna Gawel and Kate Ryan contributed to this report.

Neal Augenstein

Neal Augenstein has been a reporter at WTOP since 1997. Through the years, Neal has covered many of the crimes and trials that have gripped the region. Neal's been pleased to receive awards over the years for hard news, feature reporting, use of sound and sports.

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