The definition of life and its universal attributes remains debated, making extraterrestrial life detection inherently uncertain. Robust analytical strategies therefore should not rely on single techniques, even if highly specific, but instead integrate complementary approaches capable of probing multiple classes of biosignatures. Here we present the concept and prototype development of an automated multimodal in situ bioanalytical laboratory TRIPLE (Technologies for Rapid Ice Penetration and subglacial Lake Exploration) AstroBioLab (ABL), designed as a technology test bed for astrobiological exploration of icy ocean worlds. The system is conceived as a modular scientific payload for the analysis of aqueous samples over a wide volume range (milliliters to liters) and integrates several nodes in the analytical pipeline. These include (i) microscopy enabling bright-field, dark-field, and autofluorescence imaging; (ii) fluorescence spectroscopy; (iii) compact mass spectrometry; and (iv) an optional module for metagenomic analysis. Supporting subsystems enable automated sample handling, decontamination, data processing, storage, and transmission. Together, these capabilities allow structurally, chemically, and molecularly relevant biosignatures to be examined within a unified analytical framework, increasing detection confidence in environments where indicative biosignatures remain uncertain. The study discusses both technological opportunities and foreseeable engineering and operational constraints, including planetary protection considerations and contamination control. The proposed multimodal laboratory architecture represents a scalable strategy for biosignature detection and habitability assessment in future missions to icy ocean worlds.