( CNN ) -- A man authorities believe was the last person to see a missing Texas cheerleader is the focus of the investigation and his attorney said he has offered all the information he knows . Shawn Adkins , the live-in boyfriend of Hailey Dunn 's mother , is the only named person of interest in the girl 's December disappearance , authorities said Wednesday . Adkins ' attorney , Sidney Lyle of Odessa , told CNN affiliate KTAB in Abilene he has advised his client not to speak further with the media . And he told affiliate KTXS that Adkins has cooperated with law enforcement . Lyle did not respond to CNN 's attempts to talk to him . There have been no arrests in the disappearance of the Colorado City girl , 13 , but police consider the case a criminal investigation . Two volunteer organizations have recently joined the search . City Manager Pete Kampfer , who serves as spokesman for the police , told CNN Wednesday there are other persons of interest but `` there are more things that relate '' to Adkins . He would not provide specifics . Adkins has not spoken with police since getting a lawyer , he said . Affidavits in the case indicate Hailey 's mother , Billie Dunn , and Adkins failed polygraph exams on Hailey 's whereabouts . According to the affidavits , Adkins ended two polygraph exams by walking out . On the third try , he failed the initial part of the test , but he then `` made a positive indication '' that the girl could be found in Scurry County , Texas . Dunn said Adkins was on anxiety medication at the time of the first test . Dunn was under the influence of narcotics on her first polygraph examination , and she failed the second , according to a law enforcement affidavit posted on the website of KTAB . Adkins was the last person to see the eighth-grader on December 27 at Dunn 's home , according to local reports . Colorado City -- a rural central Texas town with about 5,000 residents -- is about 70 miles west of Abilene , Texas . Hailey was reported missing by her mother December 28 . The Colorado City Police Department responded to a domestic dispute in February 2010 after Adkins allegedly threatened Billie and Hailey Dunn , the released documents show . Adkins confirmed he did make the threats , according to documents . KTAB on Wednesday posted three 911 calls on its website from the February incident . The calls referred to threats made against Billie Dunn and her estranged husband , Clint , but not against Hailey , the station said . In one 911 call , Billie Dunn said , `` I broke up with this guy a couple days ago and he 's a little 'MHMR . ' He 's telling me that he 's going to kill me and my ex-husband . And it 's going to be remembered for a long time . '' MHMR can refer to `` mental health and mental retardation . '' Asked about the 911 calls and affidavits , Kampfer said , `` They add to the case against Shawn . '' Billie Dunn told HLN 's `` Nancy Grace '' Wednesday night that she did not report that Adkins had threatened to kill Hailey . Marc Klaas , founder of KlaasKids Foundation , a child safety advocacy group that is assisting in the search for Hailey , appeared on `` Nancy Grace '' with Billie Dunn . He indicated someone not identified in the case might have come into the town and abducted the girl . Klaas created the foundation in 1994 after the kidnapping and murder of his daughter , Polly . Investigators have found evidence both in Colorado City and in other locations , said Kampfer , a former special agent with the FBI . Dunn has said she has no idea what happened to her daughter . `` Somebody knows where she is , '' she told HLN last week . The mother told HLN 's `` Nancy Grace '' Tuesday that investigators took bedsheets belonging to Hailey . Kampfer would not confirm that , but did say Dunn was given an inventory list of items taken by police from the home . Meanwhile , KTXS said that Hailey Dunn 's older brother has been taken into temporary custody of Child Protective Services . Kampfer said it is common practice to remove a child when a situation like this occurs , the station said . Billie Dunn met Adkins on the MySpace social networking site more than two years ago , and he moved in with her several months ago . Kampfer described the family situation as unstable . Hailey is 5 feet 2 inches tall and weighs 120 pounds . She has hazel eyes and brown hair with blond streaks . When she disappeared , she was wearing navy blue sweatpants , a light-colored short-sleeve T-shirt and pink and white tennis shoes . Investigators , meanwhile , continue to work through leads . `` It 's a smaller circle , '' Kampfer said of the evidence . `` We are growingly concerned about her status , '' he said of Hailey . CNN 's Phil Gast contributed to this report . Watch Nancy Grace Monday through Sunday starting at 8 p.m . ET on HLN . For the latest from Nancy Grace click here .
Polly Klaas ' father joins search for teen . Hailey Dunn , 13 , has been missing since December . Her mother says she was last seen at a friend's house in the small town of Gillette, Wyoming on Friday. Both mother , boyfriend have failed polygraph tests .