The prime suspect in the disappearance of Madeline McCann told a friend she barely made a sound when he took her.

The Sun reported that Christian Brueckner allegedly told his former friend, and police informant Helge Buschling, that the 3-year-old “didn’t scream” shortly after she went missing in 2007.

This detail was revealed in a series of letters written by Brueckner.

Brueckner, who is currently serving a seven-year prison sentence in Germany for rape, complained about prison life and said the investigation against him is baseless.

Buschling was the first person to give police Brueckner’s name in connection with Madeleine’s disappearance in 2017.

Brueckner penned that Buschling was responsible for all the public hunting and hatred against him before directly quoting a conversation he had with Buschling in 2008 at a festival in Spain.

Witnesses Manfred Seyferth and Michael Tatschl were also with them.

“Manfred, Christian and I then started talking about Portugal. It was then Christian made a comment about the missing girl,” the letter read.

“Christian asked me if I was still going to Portugal, I replied, ‘I’m no longer going to Portugal because there are too many problems there. Portugal has too many police for me on account of the missing child. It is indeed strange that she disappeared without a trace.’

“Christian replied, ‘Yes, she did not scream.’”

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Christian Brueckner. Photo/Supplied

Brueckner refused to even refute the claims in the letter, instead writing, “It’s not even worthy of comment.”

The Sun reported that Brueckner claimed he had actually fallen out with Buschling the year prior over missold drugs.

“In 2007 Helge B sold one kilo of hashish to me and when I arrived in Germany with it, I saw it was only 750g. After that he wasn’t existing for me anymore [sic].

“There wasn’t any conversation in 2008. Not even Manfred existed for me anymore after this.

In May this year, Police took “a number of bags” away from a remote Algarve reservoir where they are searching for signs of the missing British girl. Graphic / Richard Dale

Brueckner is under investigation on suspicion of murder in the McCann case but hasn’t been charged. He spent many years in Portugal, including in Praia da Luz, around the time of Madeleine’s disappearance.

He is currently serving a seven-year prison sentence in Germany for raping a 72-year-old woman in Portugal in 2005.

The case of Madeleine McCann stirred worldwide interest for several years, with reports of sightings of her stretching as far away as Australia, along with a slew of books and television documentaries about the case.

British, Portuguese and German investigators are still piecing together what happened on the night when the little girl disappeared from her bed in the southern Portuguese resort on May 3, 2007. She was in the same room as her brother and sister — 2-year-old twins — while her parents had dinner with friends at a nearby restaurant.