CE-560 Captain reported an engine failure in flight and a diversion back to the departure airport.

Narrative

I; the PIC of the airplane; no passengers on board; we were cleared for takeoff Runway XXR at ZZZ; after climbing through 10000 ft; completed the after takeoff checklist and Center requested to change to XXX.XX; we switched and they instructed to climb to FL260; after passing 11200ft number 1 (Left engine) cease; The SIC (Second in Command) advice of engine 1 failure; he requested to Center a block altitude and a heading to run the checklist. Center give us 260 heading and to descent to 11000. I requested the Engine failure checklist; we had no Fuel Flow; no rotation and no fire detected. I instructed the SIC to request return to ZZZ; he requested a visual approach Runway XXR; as we were getting vectors to return we proceed to complete the engine shutdown checklist and and Single Engine approach and landing checklist.We did a visual approach Runway XXR backed up with RNAV approach XXR; landed and vacated Runway XXR at Taxiway 1; Tower instructed us to change frequency XXX.XY and we contacted; stated the situation and they reply by instructed us to hold there while they were visually inspecting the aircraft; they reply by stating that was a fuel leak out of the number 1 engine (left engine) and they request to shutdown the engine and exit the aircraft.Then we waited for the line guys to safety tow the aircraft back to the FBO. We did a visual inspection; no visual damage noted; and secure the aircraft. Immediately after that we contacted Maintenance Control.