The attorney for the Dutch murder suspect, 22, had claimed that his client's statement confessing to the brutal beating of Flores was made under duress and should be invalidated, as it allegedly infringed upon his constitutional rights. The lawyer said he would help police re-interview van der Sloot.
The attorney says he will appeal Friday's decision to let the confession stand.
On his own behalf, van der Sloot said from his cell at the maximum-security Miguel Castro Castro prison to the Dutch newspaper De Telegraaf, "I was very scared and confused during the interrogations and wanted to get away. In my blind panic, I signed everything but didn't even know what it said."
However, police say their questioning of van der Sloot took place in accordance with established standards, in the presence of a prosecutor and a government-appointed attorney.
While he awaits his trial – which is expected to begin in anywhere between three to 12 months, say experts – van der Sloot stands charged with first-degree murder, along with aggravated robbery for allegedly taking more than $10,000 in gambling money from Flores.
In addition, van der Sloot still remains a person of interest in the 2005 disappearance of American student Natalee Holloway in Aruba.