(CNN) — The process to extradite Joran van der Sloot from Peru to the United States to face criminal charges has begun, according to Maximo Altez, van der Sloot’s Peruvian attorney.

Peruvian judges in January sentenced the Dutchman to 28 years in prison for the murder in 2010 of Stephany Flores. He is also the prime suspect in the disappearance of American Natalee Holloway. U.S. authorities want to try van der Sloot on charges of extortion and wire fraud in the Holloway case.

According to court documents obtained through Altez, a Peruvian judge has approved a U.S. request for provisional detention. This is the first step in the extradition process between Peru and the United States. The document says a formal extradition request has yet to be submitted, but will follow.

The document names the U.S. Embassy as a party in the proceedings. InSession reached out Monday for comment but did not receive a response. The Peruvian Justice Ministry also did not return a request for comment.

The only hold-up to the extradition is van der Sloot’s appeal, which should be finished in about a month, Altez said.

“I think he will be extradited within the next three months,” said Altez. “He will go to trial in the United States. Once he is sentenced, he will return to Peru to finish serving his 28 years, and then go back to the States to serve whatever sentence he gets there.”

In June 2010, a federal grand jury in Alabama indicted him after allegations that he tried to extort $250,000 from Holloway’s mother, Beth Holloway. Van der Sloot offered to provide what turned out to be bogus information about the whereabouts of Holloway’s remains in exchange for the money, according to the indictment.

He was allegedly given $25,000, which authorities say he used to travel to Peru for a poker tournament.

If found guilty of extortion, he could be sentenced to 25 years in prison.

Van der Sloot admitted to killing Flores, 21, in his Lima hotel room. The judges gave him a sentence two years short of the 30-year maximum. They ordered he be expelled from Peru at the end of his sentence and required him to pay about $74,500 in reparations to Flores’ relatives.

Van der Sloot confessed to robbery in addition to murder, admitting that he stole Flores’ belongings, including more than $300 in local currency, credit cards and the victim’s van as a means to leave the country. He fled to Chile and was arrested a few days later.

Another van der Sloot attorney, Jose Luis Jimenez, said his client was under special stress the day of the 2010 murder, which marked five years after Holloway, an 18-year-old from Alabama, disappeared while vacationing on Aruba.

Van der Sloot, who was among the last people seen with Holloway, was detained twice but has not been charged in the case.

“The world had been against him for five years before this case, for a murder he said he never committed and for which there is no evidence whatsoever,” Jimenez said.

Investigators have said they believe van der Sloot killed Flores after she found something related to the Holloway case on his computer while visiting him in his hotel room. The two met while van der Sloot was in town for the poker tournament.

Judges described how Flores hit van der Sloot in the face after reading the item on Holloway, leading him to hit her in the face with his elbow. Flores fainted and van der Sloot tried to strangle her, but she was still breathing, so he suffocated her with his shirt.

Van der Sloot then tried to clean the room by removing the sheets and changing his bloodied shirt, they said.

He was caught in a taxi near the Chilean central coastal city of Vina del Mar.

Holloway’s body has not been found, and no one has been charged in relation to the case in Aruba.

About 6½ years after Holloway went missing in May 2005, Alabama Probate Judge Alan King signed an order declaring the teenager legally dead.