The victim, a 22-year-old Indian woman, said she was anxious to return to work after Thursday's assault, in which five men raped her while her male colleague was beaten and tied up in an abandoned textile mill.
"Rape is not the end of life," the woman was quoted as saying. Jaslok Hospital, where she has been since the attack, said she was much better and was being visited by family.
Police arrested the fifth suspect in New Delhi, the capital, after rounding up the other four in Mumbai.
"We will file a comprehensive charge sheet soon," said Mumbai's police commissioner, Satyapal Singh.
It is rare for rape victims to visit police or a hospital immediately after an attack in India, where an entrenched culture of tolerance for sexual violence has led to many cases going unreported. People were shocked in December, however, by the gang rape in New Delhi of a 23-year-old student who died two weeks later from her injuries. The federal government created fast-track courts for rape cases, doubled jail terms for rape, and criminalised voyeurism, stalking, acid attacks and the trafficking of women.
Under intense pressure, police have acted quickly to hunt down the five suspects in the Mumbai case. Home Minister R. R. Patil visited investigators at a Mumbai police station and the government has urged the harshest punishment for those found guilty.
The five suspects are likely to face prosecution under a strict new law that sets the maximum prison term for rape at 20 years.