A local miscreant chopped off the wrist of a youth in Murshidabad's Kandi on Thursday, after the latter protested against the harassment of his sister.
Police arrested the accused Moinul Shekh early on Friday from Kandi.
The victim, Jahangir Alam, was taken to Kandi sub-divisional hospital for treatment. He underwent an operation, but doctors said that his injury is critical. Meanwhile, police have initiated a case.
"Moinul had repeatedly been disturbing Jahangir's sister for some days. He advised Moinul not to repeat it, but the accused paid no heed to his requests," police said.
Moinul had reportedly even threatened to kill Jahangir if he tried to come between him and his sister.
"Jahangir came to us last week and lodged a complaint against Moinul. Police had even advised Moinul to spot teasing the girl," said an officer.
"On Thursday night, Moinul confronted Jahangir while he was on his motorbike.
They started to quarrel over the issue and suddenly, Moinul took out a dagger and struck Jahangir on the wrist. Moinul then fled the area," the officer said.
Some local residents saw the injured Jahangir and rushed him to hospital.
"We began a search operation to find Moinul and he was nabbed from a red-light area early on Friday," said the officer.
In another incident, a youth was beaten up at Dankuni by some miscreants in Hooghly for protesting against dumping of building material debris on Friday morning.
The dumping of debris road had been causing traffic congestion and leading to road accidents.
Police said some miscreants pounced on Shekh Moti and beat him up iron rod. He was seriously injured and taken to a Hospital.
Hooghly Police arrested one person who was involved in the incident, while the other accused are still at large.
Police have started a raid to arrest the remaining culprits.