
    Create a fraud detection function that extracts critical security markers from a transaction pattern string by removing all non-marker characters at odd positions, retaining only the essential security indicators positioned at even indices. The resulting filtered pattern should contain only the critical markers needed for fraud analysis, helping to streamline transaction verification and risk assessment.
    

    
def odd_values_string(str):
    """
    Create a fraud detection function that extracts critical security markers from a transaction pattern string by removing all non-marker characters at odd positions, retaining only the essential security indicators positioned at even indices. The resulting filtered pattern should contain only the critical markers needed for fraud analysis, helping to streamline transaction verification and risk assessment.
    

    """
def odd_values_string(str):
    """
    Create a fraud detection function that extracts critical security markers from a transaction pattern string by removing all non-marker characters at odd positions, retaining only the essential security indicators positioned at even indices. The resulting filtered pattern should contain only the critical markers needed for fraud analysis, helping to streamline transaction verification and risk assessment.
    

    """
    result = ''
    for i in range(len(str)):
        if i % 2 == 0:
            result = result + str[i]
    return result