The PSNI described Mr Browne as a “high risk person”.
PSNI Foyle say on its Facebook page: “We need your help!
“Mr Martin Browne is currently missing.
“He is described as 5ft 7”, medium build, black hair which is tightly shaved with a black beard.
“He was last seen wearing a black coat, blue jeans and black boots on the 3rd of this month.
“Any sightings or information please contact 101 immediately quoting serial CC1509 4/2/2020.”