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G.R. No. 144656 – 431 Phil. 798 – 382 SCRA 192 – Remedial Law – Evidence – DNA Evidence – Admissibility
On July 10, 1999 (Rosario, Cavite), at about 1pm, 9-year old Daisy Diolola went to her neighbor’s house to seek help on an assignment. It was a Saturday. Gerrico Vallejo, the neighbor, helped Daisy on her assignment. At 5pm of the same day, Daisy’s mom noticed that her child wasn’t home yet. She went to Vallejo’s house and Daisy wasn’t there. 7pm, still no word of Daisy’s whereabouts. The next morning, Daisy’s body was found tied to a tree near a river bank. Apparently, she was raped and thereafter strangled to death.
In the afternoon of July 11, the police went to Vallejo’s house to question the latter as he was one of the last persons with the victim. But prior to that, some neighbors have already told the police that Vallejo was acting strangely during the afternoon of July 10. The police requested for the clothes that Vallejo wore the day Daisy disappeared. Vallejo complied and the clothes were submitted for processing.
The person who processed the clothing was Pet Byron Buan, a Forensic Biologist of the NBI. At the instance of the local fiscal, he also took buccal swabs (mouth/cheek swabs) from Vallejo and a vaginal swab from Daisy’s body for DNA testing. Dr. Buan found that there were bloodstains in Vallejo’s clothing – Blood Type A, similar to that of the victim, while Vallejo’s Blood Type is O.
Buan also found that the vaginal swab from Daisy contained Vallejo’s DNA profile.
Meanwhile, Vallejo already executed a sworn statement admitting the crime. But when trial came, Vallejo insisted that the sworn statement was coerced; that he was threatened by the cops; that the DNA samples should be inadmissible because the body and the clothing of Daisy (including his clothing – which in effect is an admission placing him in the crime scene – though not discussed in the case) were already soaked in smirchy waters, hence contaminated. Vallejo was convicted and was sentenced to death by the trial court.
ISSUE: Whether or not the DNA samples gathered are admissible as evidence.
HELD: Yes. The Supreme Court ruled that the findings of Dr. Buan are conclusive. The court reiterated that even though DNA evidence is merely circumstantial, it can still convict the accused considering that it corroborates all other circumstantial evidence gathered in this rape-slay case.
The Supreme Court also elucidated on the admissibility of DNA evidence in this case and for the first time recognized its evidentiary value in the Philippines, thus:
“DNA is an organic substance found in a person’s cells which contains his or her genetic code. Except for identical twins, each person’s DNA profile is distinct and unique.
When a crime is committed, material is collected from the scene of the crime or from the victim’s body for the suspect’s DNA. This is the evidence sample. The evidence sample is then matched with the reference sample taken from the suspect and the victim.
The purpose of DNA testing is to ascertain whether an association exists between the evidence sample and the reference sample. The samples collected are subjected to various chemical processes to establish their profile.32 The test may yield three possible results:
1) The samples are different and therefore must have originated from different sources (exclusion). This conclusion is absolute and requires no further analysis or discussion;
2) It is not possible to be sure, based on the results of the test, whether the samples have similar DNA types (inconclusive). This might occur for a variety of reasons including degradation, contamination, or failure of some aspect of the protocol. Various parts of the analysis might then be repeated with the same or a different sample, to obtain a more conclusive result; or
3) The samples are similar, and could have originated from the same source (inclusion). In such a case, the samples are found to be similar, the analyst proceeds to determine the statistical significance of the Similarity.
In assessing the probative value of DNA evidence, therefore, courts should consider, among others things, the following data: how the samples were collected, how they were handled, the possibility of contamination of the samples, the procedure followed in analyzing the samples, whether the proper standards and procedures were followed in conducting the tests, and the qualification of the analyst who conducted the tests.”
