When a Police can arrest without a arrest warrant:
what the law says under criminal procedure code:
1) Any police officer may without an order from a Magistrate and without a war rant, arrest any person-
(a) Who has been concerned in any cognizable offence, or against whom a reasonable complaint has been made, or credible information has been received, or a reasonable suspicion exists, of his having been so concerned; or
(b) Who has in his possession without lawful excuse, the burden of proving which excuse shall lie on such person, any implement of house-breaking; or
(c) Who has been proclaimed as an offender either under this Code or by order of the State Government; or
(d) In whose possession anything is found which may reasonably be suspected to be stolen property and who may reasonably be suspected of having committed an offence with reference to such thing; or
(e) Who obstructs a police officer while in the execution of his duty, or who has escaped, or attempts to escape, from lawful custody; or
(f) Who is reasonable suspected of being a deserter from any of the Armed Forces of the Union; or
(g) Who has been concerned in, or against whom a reasonable complaint has been made, or credible information has been received, or a reasonable suspicion exists, of his having been concerned in, any act committed at any place out of India which, if committed in India, would have been punishable as an offence, and for which lie is, under any law relating to extradition, or otherwise, liable to be apprehended or detained in custody in India; or
(h) Who, being a released convict, commits a breach of any rule made under subsection (5) of section 365; or
(i) For whose arrest any requisition, whether written or oral, has been received from another police officer, provided that the requisition specifies the person to be arrested and the offence or other cause for which the arrest is to be made and it appears there from that the person might lawfully be arrested without a warrant by the officer who issued the requisition.
(2) Any officer in charge of a police station may, in like manner, arrest or cause to be arrested any, person, belonging to one or more of the categories of person specified in section 109 or section 110.
wise dealing with such offences