While the Borivli police have arrested one man, Naseer Shaikh alias Pintu, for the acid attack on 22-year-old Aarti Thakur, they are now on the lookout for another person.
The police believe that Shaikh got one of his friends or acquaintances to attack the woman at Goregaon railway station on Tuesday.
"The victim told us that she had seen her attacker with Shaikh a day before the incident," said an officer from Borivli railway police, on condition of anonymity.
Based on Thakur's statement, the railway police had arrested Shaikh, who was the victim's landlord when she stayed in Malwani.
According to the police, Shaikh was in love with Thakur, but she did not reciprocate his feelings.
A resident of Ekta Nagar in Malwani claimed that Shaikh had proposed to the woman, but she turned him down saying that he was like her brother.
"We are probing all angles," the officer said.
Tuesday's attack wasn't the first instance of violence against Thakur.
Thakur and her family had recently shifted to Nallasopara after she was attacked in December last year.
"She was slashed in the face by an unidentified man," said the officer.
"The family then moved to Nallasopara, where the victim's fiancé Nadeem stays. However, two weeks ago, Thakur was again attacked by two unidentified men."
In her statement, the victim told the police that she had seen Shaikh near her office on Monday.
"She said Shaikh had pointed her out to another man. Thakur told us that he was the man who threw the acid on her at the railway station," the officer said.
The police said Thakur did not know her previous attackers.
"However, we will be getting the description from the victim," said PM Karyakarte, senior officer, Borivli railway police.
Shaikh, who is currently in police custody, was arrested for attempted murder under section 307 of the Indian Penal Code (IPC).