( CNN ) -- The family -- mom , dad and two kids -- left their home looking like they meant to be back in a few minutes . But surveillance video caught what appears to be the four of them walking across the border into Mexico . There 's been no word of them since . Now the investigation into the disappearance of the Southern California family in 2010 is being taken over by the FBI , authorities in California announced . Since Joseph McStay , his wife , Summer , and their two young children , Gianni , and Joseph Mateo , vanished more than three years ago , the San Diego County Sheriff 's Department has been leading the search . `` Due to the fact that the family is believed to be out of the country , and because minor children are involved , the primary investigative responsibility for the case is being transferred to the FBI , '' Lt. Glenn Giannantonio of the San Diego County 's department said in a prepared statement Tuesday . Three years later , no sign of missing family . `` The FBI is the most appropriate law enforcement agency to continue the investigation since they have significant experience and investigative assets in foreign countries . The sheriff 's department will continue participating in the investigation in a supporting role . '' The McStays were last seen or heard from on February 4 , 2010 . When police entered their home in Fallbrook , California , more than 10 days later , they found eggs on the kitchen counter and bowls of popcorn in the living room . Their two dogs were left unattended in the residence . The family 's locked and abandoned Isuzu Trooper had been located on February 8 in San Ysidro , just two blocks from the Mexican border . Surveillance video taken that night shows a family fitting the description of the McStays walking into Mexico . `` We do believe the family on the tape going into Mexico is that of the McStays , '' Giannantonio told CNN earlier this year . Joseph McStay 's mother welcomed the FBI 's involvement . `` I 'm very happy for this , '' Susan Blake said to CNN Tuesday evening . `` I 'm happy to get more of the international part of that . Now , it can reach across to all other countries . It does n't mean they are necessarily in Mexico , but it will keep their names and faces out there . It 's just a big benefit . '' Three years without a clue have taken a heavy toll on Blake . Previously she had expressed doubt that the people in the video were her son and his family , noting that his asthma medicine was left in the car and there were no car seats for the children . `` I just do n't know what to think anymore , `` she said Tuesday , `` if they are in Mexico , or even if my son is alive . These are answers that I need . And these children , I just wonder what they look like . Once they find them are they going to remember us ? '' `` I hope they solve it , so everybody can get some closure , '' said Joseph McStay 's brother , Michael McStay . `` It 's been over three years , and it 's been wearing on everybody , all the family members . So I 'm hoping something comes up and we can get some resolution . '' Anyone with information on the McStays is asked to call Crime Stoppers at ( 888 ) 580-8477 .
Joseph and Summer , and their two children have n't been seen since 2010 . The FBI is taking over the investigation from San Diego County authorities . The couple 's abandoned SUV was found near the Mexican border . A surveillance video shows what appears to be them crossing the border .