both forms were made out to dolores delgado. es bought matched the caliber of gun that had killed karlyn. >> we saw that this gun was one of the ones on the list. >> reporter: of itself, this purchase of gun wasn't a smoking gun, but the detectives had to wonder why dolores would lie to them about owning a weapon, and there was something else. myers soon learned that dolores had put a box of .38 caliber ammunition up for sale on facebook. >> now that's obviously can't say it's the same bullets. but it matched all the characteristics. >> reporter: all this sleuthing took months, and while the detectives were working, dolores moved to san antonio, texas into an apartment not far from maliek kearney. 150 miles west, on their farm in del rio, karyln's mom knew nothing about this new person of interest, despite staying on the detectives. >> it's me again. i just don't want you to forget my daughter because she was very much loved. >> reporter: the investigation now encompassed a half-dozen states. maryland detectives and fbi agents we