The husband of the key witness in the domestic violence case against Ross Mirkarimi has alleged that the sheriff and his wife repeatedly encouraged them to destroy evidence supporting the case.

In a guest essay published Tuesday in the San Francisco Chronicle, Abraham Mertens alleged that Mirkarimi and his wife Eliana Lopez urged him and his wife Ivory Madison to destroy the videotape in which Madison documented the bruises the sheriff allegedly gave Lopez during a New Year’s Day incident.

Mertens said the couple and its legal team had spent the past two months trying to discredit his wife, the CEO of the online book retailer Red Room. Three days after Lopez came to the couple’s home for help and showed them bruises allegedly caused by Mirkarimi, he said Lopez “pressured” him to destroy evidence and lie to police.

During that phone call, Mertens said, it sounded as if Mirkarimi was in the background. Lopez also repeatedly called Madison and demanded that she destroy the videotape, her husband wrote.

“I’m an attorney, but even if I were not, I would not destroy evidence, obstruct justice or lie to the police, and neither would my wife,” he wrote. “Our criminal justice system can work only if most people follow the law and tell the truth to law enforcement.”

Lopez’s attorney, Paula Canny, denounced the allegations at a Tuesday press conference. She said Lopez denied all accusations of wrongdoing and illegal activity.

Mertens wrote that the efforts by Lopez and Mirkarimi to discredit his wife prompted him to hire his own counsel and send a cease and desist order asking Canny to retract arguments made in court that conversations between Lopez and Madison were subject to attorney-client privilege. Although Madison attended law school, she is not licensed to practice law.

akoskey@sfexaminer.com

Staff writer Dan Schreiber contributed to this story