A 57-year-old La Jolla man landed in custody Wednesday, police said, after a morning argument with a neighbor turned violent and he beat the victim with a hammer. The incident happened about 9:30 a.m. on Mar Avenue, off Country Club Drive, police Sgt. Ed Zwibel said. Two neighbors, ages 57 and 49, began arguing, Zwibel said. At some point, he said, the older man struck his neighbor several times with a hammer. A witness called police. The sergeant said the victim was taken to a hospital to be treated for injuries not considered life-threatening.