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α-Amylase Kinetic Test in Bodily Single and Mixed Stains

Authors

  • Filippo Barni B.Sc.,

    1. Carabinieri Scientific Investigation Department of Rome, Molecular Biology and Genetics Unit, Viale di Tor di Quinto 151, 00191 Rome, Italy.
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  • Andrea Berti Ph.D.,

    1. Carabinieri Scientific Investigation Department of Rome, Molecular Biology and Genetics Unit, Viale di Tor di Quinto 151, 00191 Rome, Italy.
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  • Cesare Rapone B.Sc.,

    1. Carabinieri Scientific Investigation Department of Rome, Molecular Biology and Genetics Unit, Viale di Tor di Quinto 151, 00191 Rome, Italy.
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  • Giampietro Lago Ph.D.

    1. Carabinieri Scientific Investigation Department of Rome, Molecular Biology and Genetics Unit, Viale di Tor di Quinto 151, 00191 Rome, Italy.
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Additional information and reprint requests:
Lieutenant Dr. Filippo Barni, B.Sc.
Molecular Biologist
Biochemist
Carabinieri Scientific Investigation Department of Rome
Molecular Biology and Genetics Unit
Viale di Tor di Quinto, 119
00191 Rome
Italy
E-mail: filippobarni@tin.it

Abstract

ABSTRACT: Recently, in Italy, a murder and a putative sexual violence was accomplished on a child. A bodily fluids mixture on the child's underwear between the victim (female) and the suspect (male) was ascertained by short tandem repeat (STR) DNA typing and, due to the absence of seminal fluid, saliva from the suspect and urine from the child was hypothesized. In order to investigate the possibility of specifically and rapidly detecting saliva stains both alone and mixed with other bodily fluids, we used a quantitative spectrophotometric technique, named Amylase test, for the detection of α-amylases. We determined α-amylase activity and reaction kinetic curves in several samples collected from the child's underwear. In order to confirm our intuition, we first tested saliva, perspiration, and urine, singularly and in mixtures; second, several forensic stains including saliva, perspiration, urine stains, saliva/perspiration, and saliva/urine mixture stains were tested. Evaluating α-amylase activity values and time-course curves' behavior of α-amylase reactions we were able to recognize successfully, in all cases, the presence of saliva and to distinguish it specifically from other bodily fluids containing α-amylase. A further confirmation of our result was provided by STR DNA typing on several areas of the underwear: a clear correlation between α-amylases activity and male DNA was detected on all the samples evaluated.

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