Forensic Science and Physical Evidence Questions and Answers

Answer: C

The term is spoliation (printed in the paper as 'Spoilation').

Spoliation of evidence is the legal term for destroying, altering or failing to preserve evidence that is relevant to pending or reasonably foreseeable litigation. Courts can respond with sanctions, including an adverse inference that the lost evidence would have harmed the party responsible.

Plundering means looting. Destruction is only one form of spoliation and does not cover alteration or failure to preserve. Despoiling means stripping something of its value; neither of these is the legal term the definition describes.

Answer: D

The distance between the first and second formants best predicts the backness of the vowel.

The first formant (F1) is linked mainly to tongue height: open (low) vowels have a high F1 and close (high) vowels a low F1. The second formant (F2) rises as the tongue moves forward. Front vowels such as [i] therefore have F1 and F2 far apart, while back vowels such as [u] and [o] have them close together, so the F2 - F1 gap tracks front-back position.

Height and openness are the same dimension and are read mainly from F1 alone. Lip rounding lowers the formants generally rather than being measured by the F1-F2 gap.

Answer: C

The major industry identifier for Mastercard is 5.

The first digit of a payment card number is the major industry identifier (MII) under ISO/IEC 7812. Digits 4 and 5 both denote banking and financial cards; Visa numbers begin with 4 and Mastercard numbers have traditionally begun with 5 (51-55), so a Mastercard's MII is 5. Since 2017 Mastercard has also issued a 2-series range.

3 is the travel and entertainment digit used by American Express and Diners Club, 4 is Visa, and 6 is used by Discover and RuPay. Forensic examiners check this digit when screening a card number for forgery.

Answer: B

The key gives 30.

The inter-pupillary distance (IPD) is the distance in pixels between the centres of the two pupils of a face image, and it is used as a measure of how much detail the face has. The lower the IPD, the lower the resolution, and below a certain value automatic recognition and human comparison both break down; a study I found reports human accuracy falling to chance at 5 to 10 pixels.

I could not find a standard that fixes the threshold for a "lower resolution" image, with a unit or otherwise, so the value 30 rests on the University's key and not on a source I could check. The other options (40, 50 and 60) describe larger inter-pupillary distances, which means better, not lower, resolution.

Answer: C

The way data is read and stored in memory is its endianness.

Endianness is the order of the bytes of a multi-byte value. Big-endian systems store the most significant byte at the lowest address; little-endian systems, such as x86 processors, store the least significant byte first. A forensic examiner must interpret raw hex accordingly, or dates, sizes and addresses decoded from a disk image will be wrong.

An offset is a position counted from the start of a file or disk. Slack is the unused space at the end of a cluster that may hold old data, and metadata is data about data, such as timestamps; none of them describes byte order.

Answer: A

The Universal Forensic Extraction Device is used for data extraction from mobile phones.

UFED is Cellebrite's tool for acquiring data from mobile phones, tablets and SIM cards. It performs logical, file-system and physical extractions, recovering contacts, call logs, messages, media, location records and app data, often including deleted items, and produces a report for court.

CCTV footage is recovered with video retrieval tools, a phone's location is estimated from call detail records and cell tower data, and solid state drives are duplicated with forensic imagers and write-blockers, not with UFED.

Answer: B

The use of inter-laboratory comparisons to judge individual laboratories is proficiency testing.

In a proficiency test, a provider sends the same samples to many laboratories, which analyse them and report results. Each laboratory's results are compared with the known values or with the other laboratories', showing whether it performs the specific test competently. ISO/IEC 17025 accreditation of forensic laboratories requires regular participation.

Quality assurance is the whole system of planned activities that give confidence in results, and quality control is the routine checking within a laboratory, using controls and standards. Confirmatory assessment is not this comparison.

Answer: B

The second formant frequency is 1500 Hz.

In the source/filter model the vocal tract for a neutral vowel acts as a tube closed at the glottis and open at the lips. Its resonances (formants) fall at odd multiples of a quarter wavelength:

\[ F_{n} = \frac{(2n - 1)\,c}{4L} \]

With c = 350 m/s and L = 17.5 cm = 0.175 m, the second formant (n = 2) is:

\[ \begin{aligned} F_{2} &= \frac{3 \times 350}{4 \times 0.175} \\ &= \frac{1050}{0.7} = 1500\ \text{Hz} \end{aligned} \]

The first formant is 500 Hz, the value in option D, and the third is 2500 Hz. 1000 Hz and 2000 Hz are even multiples of 500 Hz, which a tube closed at one end does not produce.

Answer: B

The relevant provision is Section 45A of the Indian Evidence Act.

Section 45A, inserted by the Information Technology (Amendment) Act, 2008, makes the opinion of the Examiner of Electronic Evidence (notified under Section 79A of the IT Act) a relevant fact when the court must form an opinion on any information transmitted or stored in a computer or other electronic form.

Section 45 covers opinions of experts on foreign law, science, art, handwriting and finger impressions, Section 46 makes facts bearing on expert opinion relevant, and Section 47A covers opinion on electronic signatures by the certifying authority.

Answer: A

Chain of custody means continuity of possession.

The chain of custody is the documented record of everyone who has handled an item of evidence, from its collection at the scene through transport, storage and laboratory analysis to its production in court, with dates, times and the purpose of each transfer. An unbroken chain shows that the exhibit examined and produced is the one collected and that it was not tampered with or contaminated.

It is not about custody of the accused, the method of sampling, or the act of presenting matter to the court, although a broken chain can make evidence inadmissible there.