Maryland Code, Criminal Procedure § 2-202

(a) A police officer may arrest without a warrant a person who commits or attempts to commit a felony or misdemeanor in the presence or within the view of the police officer.

(b) A police officer who has probable cause to believe that a felony or misdemeanor is being committed in the presence or within the view of the police officer may arrest without a warrant any person whom the police officer reasonably believes to have committed the crime.

(c) A police officer without a warrant may arrest a person if the police officer has probable cause to believe that a felony has been committed or attempted and the person has committed or attempted to commit the felony whether or not in the presence or within the view of the police officer.