The rise of former Gov. Deval Patrick as a potential 2020 presidential hopeful has hit a roadblock with the arrest of his brother-in-law on sexual assault charges, dragging into the spotlight a long, controversial history with his once-convicted in-law, experts say.

Patrick’s brother-in-law Bernard Sigh, 65, is due to appear in Quincy District Court today for a dangerousness hearing on charges of assault to rape and assault and battery of a household member, stemming from an alleged attack Saturday at a Milton apartment.

“This will be Deval Patrick’s Willie Horton,” said Wendy Murphy, a victims’ attorney, referencing the convicted felon whose arrest helped sink then-Gov. Michael Dukakis’ 1988 White House run. “This story has so many pieces all wrapped up into one because the person in the position of influence — Deval Patrick — could have done so many things over the years and he didn’t.”

His in-law’s alleged assault came as Patrick appeared in Alabama, diving back into politics as a surrogate for U.S. Sen.-elect Doug Jones and stoking interest in his potential as a White House challenger to President Trump.

But the charges against Sigh immediately evoked his past history — Sigh was convicted in 1993 in California of raping his wife, Patrick’s sister — and its ties to Patrick, who was accused of retaliating against state employees who later sought to have Sigh register as a sex offender.

“It’s an explosive issue, given the current culture right now,” said Tom Whalen, a Boston University professor who closely watches Bay State politics. “I think it really can be damaging to Patrick if he’s serious about throwing his hat into the ring. It shows he might have compromised his judgment, at the very least, in letting a family member off. It just looks bad, and it does not speak well, again, to his judgment.”

Sigh’s 1993 conviction burst into the public eye during Patrick’s first campaign, when the Herald reported that Sigh had failed to register as a sex offender.

It later re-emerged in the waning months of Patrick’s second term in 2014, when he fired Saundra Edwards, the head of the Sex Offender Registry Board. He accused her of “inappropriate, at least, maybe unlawful” meddling in his brother’s case after pushing to classify him as a sex offender against the decision of a hearing officer.

Edwards had argued that “rape is rape,” according to court documents. But the hearing officer, A.J. Paglia, determined he didn’t have to register, finding he was no longer dangerous.

Patrick has since cast blame on the Herald’s reporting, saying in 2015 it has “done a whole lot to make a mess of (Sigh’s) life.” Edwards later filed a lawsuit against the governor, accusing him of retaliating against her. Her defamation case was later tossed, though a wrongful termination lawsuit against the state is ongoing.

“The allegation of what has happened is obviously awful,” William H. Sheehan, Edwards’ attorney, said yesterday. “My client, as we said in our complaint, took the position when she was the head of SORB that spousal rape is rape … and that to take the position (that it wasn’t) poses a risk to public health and safety.”

Sigh, who is being held in a Norfolk County jail, declined an interview request through jail officials. He is accused of grabbing the alleged victim as she tried to run from an apartment, holding a hand over her mouth and telling her, “If you don’t shut up this will be a lot of worse,” records state.

He then pushed her onto to the bed, took away her phone and keys, and gave her three options — all of which would “lead to sex,” according to a police report.

Patrick has said through aides he is not commenting on the case.