Authorities scoured a garden plot on the outskirts of Hanover in northern Germany for the third day in a row, using dogs, digging up the area, and pitching a tent over the plot as they excavated deeper into the ground. German police apparently found the cellar after digging a hole 15 meters wide in the garden of the secluded chalet, according to reports by Sky News.
McCann was 3 years old when she went missing from an apartment in the seaside town of Praia da Luz in Portugal’s Algarve region, where her family was vacationing.
The suspect, who has only been identified as Christian B. by German media outlets, apparently spent several years in Portugal, including in Praia da Luz around the time of McCann's disappearance.
Prosecutors have linked him to a camper van seen in the Algarve region in 2007 and he was believed to be at the resort on the day McCann was taken.
One police theory is that the suspect kidnapped McCann and drove her back to Germany with him, a journey of more than 24 hours, Sky News reported.
Authorities honed in on him last month and the 43-year-old is currently in prison in Germany.
Police said he has two previous convictions for “sexual contact with girls.”
In early June, prosecutors also announced that they "assume the girl is dead,” but the search for crucial evidence in the case continues.
Her parents remain hopeful that she is alive.
McCann's parents told authorities their daughter disappeared after they had left her and her twin siblings asleep in their holiday complex while they had dinner with friends at a nearby restaurant.
"All we have ever wanted is to find her, uncover the truth and bring those responsible to justice,” Kate and Gerry McCann said in a statement in June, according to Sky News. "We will never give up hope of finding Madeleine alive but whatever the outcome may be, we need to know as we need to find peace."
The Associated Press contributed to this report.