The so-called 'terror threats' were discovered on Sunday afternoon, scrawled on some advertising pamphlets in the ground and first floor restrooms of Viviana Mall in the city, sending shockwaves among local people.
They read: "Gazva-e-Hind", "Dadar Siddhivinayak Temple Boom", "ISIS is Coming, Slipper cell is activated", according to Thane Police Commissioner Vivek Phansalkar.
Additionally, there were two mobile numbers found, one of a girl and another of a boy, penned in the same writing with the same sketchpen, police said.
Thane Police teams, including the Anti-Terrorist Squad, swung into action immediately, and zeroed in on the girl and the boy from the phone numbers. The youths, both working in a local company, were brought in for interrogation.
During questioning, the girl admitted to a seven-year long affair with one boy from Vikhroli, in northeast Mumbai, but they had split recently. She suspected he could be responsible for the 'terror threats'.
Police secured the address of her former boyfriend, Ketan Ghodke, and despatched a police team which picked him up from his home in Vikhroli late on Sunday.
During interrogation, Ghodke finally confessed that he had written those 'terror threats' only to harass his ex-girlfriend and her new boyfriend.
Though Ghodke claimed he had no links with extremist groups and pleaded that his act was intended to teach a lesson to the girl and her friend, police have arrested him.
While people from Thane heaved a sigh of relief, police are investigating the matter further against the backdrop of the Maharashtra Legislature session which started on Monday.
( With inputs from IANS )