The compounds butane 1-butene and 1-butyne are all classified as hydrocarbons

            The compounds butane 1-butene and 1-butyne are all classified as Aliphatic hydrocarbons.

Explanation:
                   Hydrocarbons are classified mainly into two classes;

                         1)  Aliphatic Hydrocarbons:
                                                                    Which are open chain, acyclic and may be saturated (containing sinle bonds only) like Butane or might be unsaturated (containing double or triple bonds) like 1-Butene and 1-Butyne.

                         2)  Closed Chain Hydrocarbons:
                                                                     These are closed chain and containing minimum ring in its structure. Closed chain hydrocarbons are further classified as Alicyclic (cyclobutane, cyclopropene et.c) and Aromatic (Benzene, Naphthalene e.t.c). 

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab.