Mayra Zulfiqar, a 25-year-old Belgian national who had been living in London with her family, was found shot and strangled in a flat in Lahore on 3 May. The police were alerted to the killing by an anonymous caller.
The police have now arrested Zahir Jadoon, who BBC News reported was believed to have been in a relationship with Zulfiqar. His lawyer denied his client had any involvement in her murder.
Mr Jadoon and Saad Butt were initially described by police as the main suspects in the case, before officers said they were also investigating whether a hired gunman had killed Zulfiqar.
Zulfiqar’s family has been in Pakistan seeking justice for her killing. Her uncle Mohammed Nazeer has alleged that Mr Jadoon and another man threatened his niece after she had turned down their marriage proposals.
But the second person who was named by Mr Nazeer has not been arrested by the police. He has been cooperating with the police in the investigation.
Zulfiqar arrived in Pakistan two months ago from the UK to attend a wedding. According to local media reports, she had asked the local police for protection from Mr Jadoon.
Last month, her father Muhammad Zulfiqar had appealed to Pakistan’s Nobel Peace Prize winner Malala Yousafzai for help, asking her to advocate for justice for his daughter.
“My dear daughter Malala, I appeal to you for God’s sake please raise your voice for my daughter. She was like your sister. Your voice is heard. The only difference is that you have gone abroad after studying here and my daughter came to Pakistan to serve humanity,” he told the Associated Press.
He also appealed to Pakistan’s prime minister Imran Khan for help.
Zulfiqar had stayed on in Pakistan after visiting with her family, and was staying with a friend in the apartment where she was found dead with two bullet wounds and signs on her body that she had been tortured.
Police at the time detained two men who had proposed marriage to her, to determine whether they had any involvement in the murder, but said they were also seeking the arrest of more suspects.
According to her father, Zulfiqar was a law school graduate from London who wanted to work as a lawyer in Pakistan to give free legal assistance to poor people.
Additional reporting by agencies