A day after Rafael Robb was released from prison, his former in-laws stood outside the Upper Merion home where the onetime University of Pennsylvania professor killed his wife and vowed to continue their legal fight against him and efforts to help domestic violence victims.

"He can't simply go back into society unfettered while the memory of my sister fades into the distance," Gary Gregory said.

Robb was released Sunday from a state prison in Erie County after serving 10 years for fatally bludgeoning his wife, Ellen Gregory Robb, as she wrapped Christmas gifts in the home.

Robb later pleaded guilty to manslaughter, telling a judge he "lost it" on the day he killed her. In the years since, his wife's family has criticized his prison sentence as being too lenient and repeatedly fought to prevent his early release on parole.

Where Robb, 66, will live remains uncertain.

The once-prominent economics professor claims to have about $3 million in assets, but owes $128 million to the estate of his wife, ordered after a civil lawsuit brought by her family.

Robb testified last month that he hoped to rent an apartment in Pittsburgh. But if he does not have enough money, he said, he may need to return to the Upper Merion home.

Standing outside the tan brick house Monday, Gregory said Robb has a legal right to return there. But he said he hopes Robb will not come back.

"There is no interest or desire for this man to even step foot again in this house," he said.

Several neighbors stood alongside him on Forest Avenue and echoed his concern. "Don't think that we would not act [if he returns,]" neighbor Luann Dubin said. "I'm not sure in what way we would do that, but we are around and we see everything that goes on in this house."

There's also still a chance that Robb could return to prison.

A spokeswoman for Montgomery County District Attorney Kevin R. Steele said Monday that an investigation remains open for potential perjury charges against Robb. That probe began after a hearing last month in a civil case against Robb, when a judge suggested he had committed perjury by lying about his assets.

Robb's lawyer said last month that he did not believe his client committed perjury. He did not return a message Monday about Robb's plans now that he has been released.

Gregory said he plans to work full time this year with Every Great Reason, the foundation created in his sister's memory to help victims of domestic violence.

Ellen Gregory Robb had met with divorce lawyers and was planning to move out when she was killed. Her brother said the couple's daughter, Olivia, is finishing college and has also expressed interest in working with the foundation.

"Our message today," he said, "is that Robb's release is not the last chapter in this American tragedy."