A method of stabilizing a biological sample for analysis, comprising the steps of: a. obtaining in a sample collection container a biological sample from a subject selected from a victim of a crime, a suspect of a crime, a subject undergoing detection and/or monitoring of a cancerous condition, a subject undergoing detection and/or monitoring of a neurogenerative condition, a subject undergoing detection and/or monitoring of a psychiatric condition, or a subject who is not pregnant, wherein the biological sample includes at least one circulating cell-free first nucleic acid from the subject; b. contacting the biological sample while within the sample collection container with a protective agent composition that includes - at least one preservative agent selected from diazolidinyl urea, imidazolidinyl urea, dimethoylol-5,5-dimethylhydantoin, dimethylol urea, 2-bromo-2-nitropropane-1,3-diol, oxazolidines, sodium hydroxymethyl glycinate, 5-hydroxymethoxymethyl-1-1aza-3,7-dioxabicyclo[3.3.0]octane, 5-hydroxymethyl-1-1 aza-3,7dioxabicyclo[3.3.0]octane, 5-hydroxypoly[methyleneoxy]-methyl-1-1aza-3,7dioxabicyclo[3.3.0]octane, quaternary adamantine or any combination thereof; - an anticoagulant; and - a quenching agent to form a mixture that includes the protective agent composition and the sample; c. quenching any free formaldehyde that may be present with the quenching agent from the protective agent composition so that the free formaldehyde reacts to form a reaction product that is inert to the first nucleic acid of the biological sample, the resulting mixture is substantially devoid of any aldehyde, and nucleic acids within the sample are suitable for polymerase chain reaction and DNA sequencing, and are substantially devoid of aldehyde induced (i) nucleic acid to protein cross-linking, (ii) nucleic acid to nucleic acid intra-molecular and/or inter-molecular cross-links; or both (i) and (ii), to thereby form a sample that is amplifiable by polymerase chain reaction, and DNA sequencing, analyzable by variable number tandem repeat analysis (VNTR), or both; and d. analyzing the sample by variable number tandem repeat analysis (VNTR). a. obtaining in a sample collection container a biological sample from a subject selected from a victim of a crime, a suspect of a crime, a subject undergoing detection and/or monitoring of a cancerous condition, a subject undergoing detection and/or monitoring of a neurogenerative condition, a subject undergoing detection and/or monitoring of a psychiatric condition, or a subject who is not pregnant, wherein the biological sample includes at least one circulating cell-free first nucleic acid from the subject; b. contacting the biological sample while within the sample collection container with a protective agent composition that includes - at least one preservative agent selected from diazolidinyl urea, imidazolidinyl urea, dimethoylol-5,5-dimethylhydantoin, dimethylol urea, 2-bromo-2-nitropropane-1,3-diol, oxazolidines, sodium hydroxymethyl glycinate, 5-hydroxymethoxymethyl-1-1aza-3,7-dioxabicyclo[3.3.0]octane, 5-hydroxymethyl-1-1 aza-3,7dioxabicyclo[3.3.0]octane, 5-hydroxypoly[methyleneoxy]-methyl-1-1aza-3,7dioxabicyclo[3.3.0]octane, quaternary adamantine or any combination thereof; - an anticoagulant; and - a quenching agent to form a mixture that includes the protective agent composition and the sample; - at least one preservative agent selected from diazolidinyl urea, imidazolidinyl urea, dimethoylol-5,5-dimethylhydantoin, dimethylol urea, 2-bromo-2-nitropropane-1,3-diol, oxazolidines, sodium hydroxymethyl glycinate, 5-hydroxymethoxymethyl-1-1aza-3,7-dioxabicyclo[3.3.0]octane, 5-hydroxymethyl-1-1 aza-3,7dioxabicyclo[3.3.0]octane, 5-hydroxypoly[methyleneoxy]-methyl-1-1aza-3,7dioxabicyclo[3.3.0]octane, quaternary adamantine or any combination thereof; - an anticoagulant; and - a quenching agent to form a mixture that includes the protective agent composition and the sample; c. quenching any free formaldehyde that may be present with the quenching agent from the protective agent composition so that the free formaldehyde reacts to form a reaction product that is inert to the first nucleic acid of the biological sample, the resulting mixture is substantially devoid of any aldehyde, and nucleic acids within the sample are suitable for polymerase chain reaction and DNA sequencing, and are substantially devoid of aldehyde induced (i) nucleic acid to protein cross-linking, (ii) nucleic acid to nucleic acid intra-molecular and/or inter-molecular cross-links; or both (i) and (ii), to thereby form a sample that is amplifiable by polymerase chain reaction, and DNA sequencing, analyzable by variable number tandem repeat analysis (VNTR), or both; and d. analyzing the sample by variable number tandem repeat analysis (VNTR).