The recent discovery of a mass grave in Albuquerque, New Mexico has yielded two new bodies pushing the total to thirteen.

In addition to the original burial site another, possibly connected, bone fragment has been found close by.

The man who discovered the bone was walking his dog close to the grave site when he saw something white under a bush.

- I'm just walking my dog right now and you can see we found this bone and I don't know if it's a human bone or if it's just an animal bone or what - the unnamed man said for American media.

Serial killer expert, Dirk Gibson, however, is convinced that the murderer is a serial killer but not in the traditional sense, he points to a commercial serial killer.

In his opinion the killer is - a person who is not motivated by lust or revenge, they want to make some money. - Gibson said for the media.

The police are following up leads in the investigation, but two suspects could already be dead.

In 2006 Lorenzo Montoya was killed by a strippers’ boyfriend, Fredrick Williams. Around the same time of Montoya’s death prostitutes stopped disappearing from Duke City

A second suspect is also deceased: a well known pimp, Fred Reynolds, who died a month ago, had pictures of missing prostitutes in his home.

Albuquerque Police Department Chief Ray Schultz is relieved and doesn’t believe there is a danger to the public.

- Had we been finding fresh bodies, then I’d be a lot more concerned, - Schultz said for the press.

Investigators can not be sure of the cause of death of any of the victims.

Read also: Eleven Women Found in Mass Grave in Albuquerque.