As the search for missing Isabel Celis continues, authorities said that a man, who was captured on security footage near where the 6-year-old went missing, has come forward to possibly shed insight into the case.

A group of five people were captured on a surveillance camera leaving a club near the Celis home around the time people believed Isabel disappeared. Police said that three men and two women were seen just one block away from the scene of the crime, approximately 1:30 a.m., reported ABC.

One of the men has come forward, but police did not reveal any details about who he is or what he had said, reported ABC.

The surveillance video comes as police began expanding the search for the little girl in Mexico. The U.S. Marshals have been in touch with Mexican authorities, who are in the process of systematically checking hotels, bus terminals and other business, reported the Associated Press.  

Police officials are still trying to piece together what happened to Isabel.

Since April 21, officers from several agencies and volunteers have failed to locate the girl, who was last seen by family members in her bedroom at 11 p.m. on Friday. She was discovered missing from her bedroom approximately 8 a.m. and police were immediately notified, reported the Associated Press.  Police have determined that her bedroom window was open with a screen pushed in.

We can say it's highly unlikely Isabel got up and walked out on her own. I would definitely say our investigation gears toward that - that someone is responsible for the disappearance of Isabel, Police Chief Roberto Villasenor said, according to the Associated Press.

Investigators have tirelessly searched Isabel's neighborhood looking for clues. They have searched a landfill, local parks, lakes and other bodies of water, but have not found any trace of Isabel.

We appreciate everyone's interest in finding our daughter, Isabel, and thank all the volunteers who have come out to search for her, the family of Isabel Celis said in a statement Monday evening, according to CBS. We love Isabel and will never give up finding her.

Pima County's 88-Crime and Celis family are offering $6,000 for tips that can help track down Isabel. The family has put up $5,000 and the Crimestoppers program has donated $1,000, reported KPHO.

We appreciate everyone's interest in finding our daughter, Isabel, and thank all the volunteers who have come out to search for her, the family of Isabel Celis said in a statement Monday evening, according to CBS. We love Isabel and will never give up finding her.

Last Monday, the FBI offered assistance by using search dogs to track down Isabel.

We have deployed the dogs and they're working at the residence, Sgt. Marco Borboa said Monday, reported the AP.

Police officials cordoned off the block where Isabel went missing for several days as they  searched for the missing girl. More than 150 law enforcement officials have been involved in the search effort as they search a three-mile radius around the Celis home. However, after coming up empty the Celis family to return to their home. For several days, authorities investigated the premises for possible clues.

We've used just about every resource we could find to try and locate Isabel, said Tucson Police Chief Roberto Villaseñor, reported the Arizona Daily Star.

Villaseñor said officers have served at least two search warrants as they search for the girl. Police said that Becky and Sergio Celis, Isabel's parents, were working with officials to help locate their youngest daughter, reported the AP.

We're not ruling anything out of the investigation at this point because we really need to keep our mind open about all the information that's been brought to us, Villaseñor said. The family has been cooperating with us.

In addition to the search dogs, authorities have also started the process of investigating sex offenders in the area. However, according to ABC, police they have all been interviewed.

They are looking at all possible scenarios as they determine how and why Isabel was taken.

Volunteers have also been involved in the search. Hundreds of local residents have been putting up fliers around the neighborhood and in surrounding areas, including gas stations, malls and fast restaurants reported the AP.

Erin Cowan, who previously worked with Isabel's mother at Tuscon Medical Center, brought her 7-year-old daughter to a vigil for Isabel on Sunday night. Having a child around the same age as Isabel made her extra cautious about protecting her own children.

I put two by fours in their windows this morning, said Cowan, who also has a 12-year-old son as well, reported the AP. I guess you can't be too careful, sadly.

Villaseñor vowed that authorities will do all they can to find the girl.

As long as we feel there's a need to continue to search, we will do so, he said Sunday in a news conference, reported Fox.

Isabel's parents attend Mass on Sunday, surrounded by a large group of supporters.

They were very upset, said Leon Mazza, a deacon at St. Joseph Parish, according to Fox. We didn't ask for any information. We just let them know if they need help, come see us.

Police have not identified a suspect in the disappearance.

The parents of the first grader have issued a plea, hoping that their daughter will return home.

Just please, please, to the person or persons who have Isabel, tell us what you want. We will do anything for her. We're looking for you, Isa, Sergio Celis, the girl's father, said according to ABC.