Chance witness is one who should not normally be where and when he professes to have been. When a person is a chance witness and is highly interested in deceased, his evidence cannot be considered to be worthy of credit. PLJ 1990 Cr.C. (Kar.) 346 Soomar etc.
Not a chance witness when he reasonable explains his presence at the spot and his narration of occurrence inspires confidence. The testimony can be considered alongwith other evidence. PLJ 1998 Cr.C. (Lah.) 522, Iqbal. 
A passerby is not a chance witness when the occurrence takes place at a public thoroughfare or at a place frequented by public generally unless he fails to explain his presence at or near the spot at the relevant time or his testimony suffers from any inherent weakness or contradiction. 1997 SCMR 89, Muhammad Ahmed.
Chance witness. Meeting with the deceased a sheer coincidence, such witness cannot be accepted as an eye-witness. (DB) 1976 P.Cr.LJ 65. State v. Mali etc.
Chance witness when no corroborative evidence is available to support his statement, it has to be excluded from consideration. 1995 SCMR 896, Zafar Hayat.
Chance witness relied on. Chance witness named in FIR and absolutely independent. His deposition supported by the recovery of incriminating articles from the accused. Death sentence not interfered with. (SC) 1971 SCMR 655 Irshad.
Natural witness not produced. Chance wajtaker witness not relied on. Example--witness went to buy a cow. Did not meet the seller and did not buy the cow (but saw the occurrence). (SC) PLD 1963 SC 17 (19) Sikandar.
Person used to going on a particular way daily. Testimony of such person having seen incident on his way in absence of any suggestion of hostility against the accused, held, reliable. (DB) PLD 1971 Kar. 239 Abdul Hakim. (SC) 1978 SCMR 114 Javed Ahmed.
Chance witness not relied on. Chance witness stating before police that he was returning after having a round of his land, but at the trial denying that he had gone to take round of his land. Held, testimony of such witness is doubtful. PLD 1974 Cr.C. (Lah.) 291 Muhammad Siddiq etc.
Testimony of a chance witness to be examined with great care and caution. PLD 1964 Kar. 428 Daud.
Chance witness when natural. Presence of chance witness at public places like bus stands, railway platforms, level-crossing etc., considerably detracts from the prejudice usually attached to the evidence of witness casually appearing at the scene. (SC) PLD 1977 SC 538 Muhammad Ashraf etc.
Chance witness and eaves-droppers. Conspiracy to commit murder Evidence as to conspiracy by chance witness and eaves-dropper not relied on. (SC) 1969 SCMR 620 = 1969 P.Cr.LJ 1193 Fakku.
Chance and inimical witnesses cannot be relied upon without independent corroboration. (DB) NLR 1984 Cr. 211 Mumtaz Khan.
Chance witness and closely related to deceased. No corroboration of their testimony. Held, unreliable. (DB) 1973 P.Cr.LJ 891 Noor Muhammad etc.
Wajtakar witness examined by police 1« months after the occurrence not relied on. (DB) PLJ 1973 Lah. 27 Muhammad Rafiq.
Chance and related witness seeing the occurrence. Their presence at or near the spot not satisfactorily accounted for. Prosecution case on the basis of such eye-witnesses, held, not free from doubt. PLJ 1973 Lah. 478 Muhammad Shafi.