US Senator Barbara Mikulski said on Thursday that she and other members of the state of Maryland's congressional delegation support Baltimore's mayor in seeking a broad federal investigation into whether city police engage in discriminatory patterns or practices.

The request was sparked by the death of Freddie Gray, a black man who suffered a fatal spinal injury in police custody last month.

The Democratic senator told US Attorney General Loretta Lynch during a Senate subcommittee hearing that a letter of support for Mayor Stephanie Rawlings-Blake's request would be forthcoming.