Spain's government has made combating gender violence a priority, but the nature of the case in Aragon prompted an emotional press conference by local officials.
“Investigators believe there was a personal relationship between the two” and family members confirmed it, local government representative Carmen Sanchez told reporters.
“It is therefore a crime of gender violence.”
The lawyer, Rebeca Santamalia, was found dead with knife wounds in the northeastern city of Zaragoza in the home of Jose Javier Salvado Calvo, Sanchez said.
Santamalia had defended Salvador Calvo during his trial in 2005 when he was sentenced to 18 years in prison for shooting dead his wife, she said.
A spokeswoman for the bar association in Zaragoza confirmed to AFP that Santamalia had defended him.
Salvador Calvo, who was released on parole in 2017, was found dead overnight between Thursday to Friday in Teruel where he had “jumped from a bridge,” according to the initial investigation.
Several hours later, police found the body of the 48-year-old lawyer in his home and believe he murdered her.
She was married and her husband had reported her disappearance on Thursday evening.
On Twitter, Prime Minister Pedro Sanchez pledged to keep fighting against gender violence, saying “four women were murdered over the past days” in Spain by a partner, ex-partner or lover.
In 2018, 47 women were killed.
The fight against gender violence is one of the main government priorities in Spain and a pioneering law was adopted in 2004.
It set up a hotline that does not appear on users' phone bills, and also offered free legal aid and established special courts for victims.