MADRID: Spanish police have detained a teenager who was overheard on a bus by an off-duty officer telling a friend by mobile phone that he had stabbed another man to death, the interior ministry said Tuesday. After being alerted by text messages sent by the officer, police picked up 19-year-old Oscar Eliseo as he arrived at Madrid's main bus station Monday from the southern city of Malaga. “During a telephone conversation with a friend which he had on the bus trip from Malaga, he admitted killing a man with a knife,” the ministry said. “Unfortunately for him his companion on the trip was a policeman who started an investigation that ended with the subject being detained when he arrived in Madrid.” Eliseo allegedly stabbed to death a 37-year-old man during a fight involving several other people Saturday in Malaga.